Despising my boyfriend

I have a 4yr old and a 2 month old and I despise my boyfriend. He works 3rd shift and is never around. My 4yr old is not his and I did not have a good experience with her father since he decided he just didn't want to be a dad when she was a month old so I was stuck doing everything on my own. I had specifically told my current bf not to take 3rd shift when we found out I was pregnant because it would leave me all alone and I would end up hating him since I had been through doing everything on my own before. He pled his cases saying he would still help and help a lot on weekends. I'm finishing my Bachelors online and he hasn't lived up to his word and isn't helping on the weekends so I can finish what I need to for my school without the kids interrupting me. I feel like I'm in the same spot as I was with my ex and I hate it, I hate having to do EVERYTHING! I asked for an equal when I started dating him not another child I had to take care of. After 2 yrs of dating and he still cannot step up now that he has a baby to take care of, I don't know what to do. I can't leave because I can't afford it all on my own but I feel like I can't stay either because I'm really starting to despise him and everything he does. I want things to change but I literally can only ask, cry, plead to him so many times to change and step up before it because detrimental to my emotional health, I don't want to end up in a deep depression since I suffer from that and spiral down. My kids are my life and have helped me see that I can focus in other thing and be happy but this is just putting me in a horrible place and I don't know what to do.