Need some advise please !

Sorry I wrote a book here lol!

So I’ve been with my fiancé for 3 years now we’ve been living together for 1. I have my son from another guy and he has a little girl from previous relationship. Anyways we’ve always argued because I never thought he paid much attention to my son. Every time we fight he always ends it with I’ll try harder or I will change. He does for like a week and then goes back to ignoring him. He never goes to any school event (awards family night etc) today my son had his last soccer game my sf told me he was going to go. He ended up not showing up. I’m so upset his excuse was that his mom needed him to pick up an inhaler because she has asthma. He has two other sister and one of them live with her 😒 so why could they go or ok he could of gone and then showed up to half time. He then starts turning it on me saying that I don’t care about his family I told him no my sons happiness comes first. So now I’m honestly thinking of moving out I’m done making excuses for him or thinking he’s going to change. My son deserves someone who’s going to support him in anything and be there for him. My problem is we just resigned our lease last month. So I either suck it up for a year and live as roommates or still leave my apartments. Sorry for writing a story lol.