My relationship is failing😭 HELP

So here's a little background story so everyone knows what's going on. My boyfriend and I have an 18 Month old together and we have another one on the way (26 weeks and 2 days preggo). we've been together ever since our daughter was born. we've put each other through a lot of shit and we've overcome a lot in our relationship. we came from two different lifestyles so I will admit it was hard for us at first to get along. we currently are staying with a family member until we have enough saved up to get a place for ourselves. I'm currently not working so it's only his income. My boyfriend and I are around each other too much and we've tried everything... I don't want to lose him but idk what else to do. I love him to death and I will admit that I am the reason we argue often. I don't want to lose him, he says there's nothing else we can do to fix our relationship but I don't want to let him go like that💔 what can I do to prove that I will work on myself and our relationship? I'm desperate!