Can't stop fighting

I need to vent. My boyfriend and I have been together for 5 years. We've been through a lot. I mean a lot! We're expecting our second child together (his third) and Idk, we fight constantly about everything. I know I'm hormonal right now, but this has been going on for at least a year. We fight mainly about money (he goes through money like it's water through his fingers) so we fall behind on bills ,which stresses me out. Plus household chores (it's possible to get any help) and caring for our oldest daughter who is 19 months. I do everything for her and it's all I can do to get him to change her diaper. I'm just tired of it and all this negativity. I feel like I have absolutely no support from him or respect (he STILL smokes in the bathroom after I've asked him multiple times to stop, plus doctor has said our daughter has a bad sensitivity to it in the way that her throat and airways get red and irritated) just no respect. I feel like it's a one way street. All about him. He whines and complains that he's sexually frustrated, but how am I supposed to be intimate with him when I feel disrespected and unsupported?? I've tried telling him thus but he just gets defensive and nasty. I feel like we're at our end and I honestly don't want that to happen, especially with a baby on the way, but there's So much negativity in our home that it doesn't even feel like a home anymore :'( Idk what to do anymore.