Don't know what to do!?

I never thought I'd be in this situation but here I am. I have 2 kiddos ages almost 5 and 2. I am currently 6 weeks pregnant. I don't know if I want to keep the baby but I don't know if I can go through with an abortion. I got pregnant with my kids dad. We have been on/off for the past 2 years due to his struggles with addiction. Overall, we have been together for 12 years but I was finally content with life and ending the relationship for good because he is just not the person I deserve. He is finally getting clean, going to therapy, and starting on medications so things have been way better than they have been but I feel having this baby will completely throw everything off. I clearly still love him and care about him but i take care of the kids, pay all the bills, and manage the house. I do everything. He's starting to help way more now that he's been clean for 4 months but it was extremely bad before and he didn't help me with our 2nd child at all (he got hooked on coke when I was pregnant). I literally had an IUD and in no way wanted to be pregnant but somehow it happened. I am 32 and always wanted more kids but now that my 2 year is almost 3 I was content with just 2. It's hard doing it on your own and it's expensive. My baby Daddy's parents help me a lot when I work and I also don't want to pressure them into watching a baby because im not sure if my guy will bail when the baby is born or relapse. I can't afford a nanny for 3 kids and pay all the bills. I also feel like this was meant to be because who gets pregnant on an IUD and maybe I am supposed to have 3 kids!? I'm extremely stressed out and have been just ignoring the problem but I need to make a decision soon. My partner has been supportive thus far and says it's my decision. He has told me that he doesn't really want another kid and fears that it will be stressful especially if the baby has any problems. Please help with any advice. I'm also terrified to get an abortion. Will it be painful? My partner was amazing when we had our first during the pandemic but things took a turn when I was diagnosed with a brain tumor and pregnant with our second. There's been so many challenges in our relationship and I feel we are just starting to be good. Please help. Thank you