Opinions on the dad not being involved with the pregnancy??

I’ve stressed the whole pregnancy about my sons dad not being involved in this pregnancy and now I am 8 months and he still hasn’t been involved. We split around the time I was 4-5 months but even then he wasn’t very involved. He always promises to check on me, or stop by to assist me for a little but he never does. He even dominates to come to appointments then texts me right before saying he can’t come.. I don’t want to stress anymore.. after so many broken promises, I just want him to go away.... the whole time he’s breaking promises with me, he’s with another chick. So a huge part of me feels like he’s brushing off the fact that we have a baby coming in a few weeks to get laid ... he also promised to get the things the baby needs and to this day he hasn’t gotten anything but when I contact him shortly after payday he’s ALWAYS 100% broke.. I’m so tired of being TIRED.. when I try to convince him that he needs to get his life together he always takes it to heart and explodes.. so in the end I feel like all the weight is on me... which isn’t the issue because I already raise two kids solo... but he knew my pain, he knew what I been through and promised to be there.. and he hasn’t .. I’m not understanding... am I doing something wrong?