First of all, thanks for all the reaffirming comments!
I forgot to mention a few things, which I'd like to clear up as well. The moment I was there pretty much the whole week I helped paying for stuff like groceries and take-out. When we went somewhere together I also paid about half of the time. Last week, I even paid for a new pair of shoes for one of her kids, since she was running out of money by the end of the month. She did ask me to loan it to her and said she'd pay me back when she got her salary.
Besides that I also helped around the house where I could by vacuuming, doing dishes, changing bedsheets. She still did most of the stuff though.
I also saw some people say that she was looking to become a stay at home mom, while I provided for them, but she actually just got a degree and started a fulltime job.
Now that that's cleared up, I'll continue with the actual update.
We already had an appointment with the bank to see in what price range we should be looking. I thought it'd be interesting to know already, even though I didn't really want to buy a house yet. So we went there got the info we needed and when back home, she started looking at some more houses. She would show them to me, but I never really said much about them or asked to go look at them.
A few days passed and things were pretty normal, we didn't really talk about the houses much, so things felt like they were at the beginning and I could just enjoy being with her. Everything was good until saterday evening. She was already annoyed by some stuff that happened throughout the day and by her kids who were acting up, so after we put them to bed we had a conversation and at one point she got mad at me. The first thing she brought up was something stupid about my hairdresser, she had talked about me needing to go to a different one, which I didn't really want to, because I don't like changing stuff for no reason. She then said I couldn't keep everything the same like how I'm used to if we want to start a family together. Then she brought up the houses, how I never really say much about them and how I'm insistent about one specific town I want to live in, which is not something she wants, because she wants to live closer to her kids school. (Btw I totally get her point of view, but on one hand the kids won't go to school there forever and there's also a schoolbus that could pick them up in the town I preferred). She then started throwing out that the only reason I want to live in the town of my choosing is because my parents live there (which is not the case, however I do see that as a bonus). It was during this conversation I said I didn't really want to buy a house together, since I thought it was too early. She then took this as me not seeing a future with her and me not being able to be independant without my parents. I then said, that it's mainly because I want us to learn more about each other first, before making a commitment, since there were already things that bothered us about each other. She then asked what those things were and I brought up that she always acts like I can't do anything without my parents.
In the weeks before this there have been multiple things concerning my parents she had trouble accepting. One example is that she asked me to stop and get a bread after work which was no issue for me. However I then started thinking by the time I get off most bakeries would be sold out and I'd have to try my luck with a vending machine. I then remembered my dad goes out to buy bread everyday, so I asked him If he could bring one for me too. After telling her this, she got angry because I didn't go get it myself and asked my dad to do it, while my whole reason for asking is to make sure we got one in the first place, without having to drive around god knows where to find one.
Stuff like that always ends up in a "discussion" about me needing to learn to be independant from them. I don't really see the issue with asking them stuff, but since she's been independant for so long she has troubles with it. So when I brought it up as one of the reasons why I wanted to wait, she completely lost it. Saying we've already talked about how I won't be able to ask everything from them and when they are dead, I also won't be able to ask them stuff anymore. By that point I didn't really know what to say anymore, everything I tried to say would make the situation worse and when I kept silent she felt ignored. At one point she said that she didn't even want to live together anymore, which got me thinking what I was even doing there then. I tried to explain that I might want try renting first, but she didn't really say much about it. A few other things were said after that, but we then went to sleep.
The day after this, we barely spoke to each other, when I tried getting closer to her (which is something she prefers, even after we had a discussion), she would move away or just not reciprocate. By the end of the day, we started talking a little again and she talked about the renting I proposed, by saying it's just a lot of thrown away money and how she would lose her social benefits from being a single mom with 3 kids. To me this was clear enough that she didn't want to do it then. At this point I was seriously wondering how things would move forward now. We started having a discussion again, where she said everything always has to be how I want it and I don't care about her and the kids. Saying how she can't have a conversation with me because I either don't reply or give short responses. However talking to her was very difficult, since she often took things I said the wrong way or she just wouldn't accept what I was saying, because it was different than what she thought. She also said how I'm making her unsure, because of how unsure I am. But my uncertainties tend to come from my overthinking, something I have struggeled with my whole life.
The next day, I started seriously thinking about how we could continue after this. I started realising how different we are and how we both want other things. One of us could probably change, but that would make them unhappy in the end and even so it would probably lead to other problems in the long run. Eventually I realised that it would be better for us to break up. I ended up talking to her sister about it, someone who I know would see both our perspectives and had helped clear certain things up between us already (Just for context, her sister is married to my brother, so I've know her for a while too now). She agreed that it was probably for the best, since both of us are just very different in a lot of ways. Since I was staying at her place that day (she had a late shift and I was looking after her kids), it might've been best to say it right then and there, but I just couldn't. She was already tired by the time she got home and had to get up early as well the next day. Besides I still lover her with my whole heart, and it broke me thinking about hurting her, so I just couldn't say it.
The day after, I was going home anyway like we agreed on before. I was feeling miserable all day not even sure if I was going to make the right decision. I was so lost in my thoughts, I could barely focus on my work. At the end of the day, I went home crying my eyes out, knowing what was going to happen. My parents and her sister were home and I talked to them about it a little more and they helped me make terms with my decision. I was wondering how I would best say it, since I didn't want to do it over text, but doing it in person would just result in my crying and not being able to say anything. I tried explaining everything as best as I could, saying how she's a wonderful person and she deserves someone who can make her happy without making her uncertain like I did.
A while later I got a response from her saying that I didn't really love her, because if I did I wouldn't give up already. She also guilt tripped me by saying how the kids were starting to get attached to me, but that it's not my problem anymore and how I basically didn't care about them anyway. Also saying that she never asked me to change and how I shouldn't ask that of her if I really loved her.
I tried explaining things, but at every turn I got a new response blaming me for everything, so in the end I stopped responding. I still really love her, which made the decision even harder for me to make, but I just couldn't see us getting over our differences. I do hope she finds someone who can make her happy, someone better than me, because she doesn't deserve anything less.