i just found out i’m pregnant with baby #4 and my husband is adamant he doesn’t want any more children

i just found out i’m pregnant with baby #4 and my husband is adamant he doesn’t want any more children. our youngest is 10m and he said he is 100% positive that that baby would be our last. i wasn’t sure i was done after 3 but wanted to revisit the conversation after our youngest turned 2. this last month hasn’t been the greatest for us, we’ve been bickering and going back and fourth a lot, not necessarily arguing but just kind of on each others nerves. because of that we only had sex once last month, and just like they say, it only takes once. i am a stay at home mom, we have 3 boys, 2 with special needs and then our 10 month old so things are really busy/hectic around here. my husband is now mad at me and blaming me for the pregnancy. saying it’s my fault that i didn’t let him get a vasectomy. i haven’t been on any kind of birth control for years bc i’ve had bad reactions to them all, and no he does not pull out or use condoms. obviously it takes 2 to make a baby but he’s making me feel like this is all my fault and i feel fucking terrible. i had an abortion when i was in my late teens and it was extremely traumatic and not something i really want to go through again but i feel like if i decide to keep this baby it may cost me my marriage. any advice and opinions are welcome, or even just words of encouragement. i don’t really have anyone except my husband to talk too about this.