What do I do?

I’m 33 weeks pregnant with my boyfriend,In back of my mind there is always doubt like it just not working no more. Since we known each other we pretty much moved in together and been with each other since..I mean things were different since we met each other the first time but everything seems to of changed. He in the past has been calling this girl babe and said she was just a friend and not to worry because she taken and liking erotic pics of other girls. I moved on and forgave him. I don’t know why I’m feeling like it just not working anymore he changed a lot since we first met each other and I’m not sure he is the same man i fell in love with,We never go on dates and he never shows much interest anymore maybe it just not meant to be...

Also his sister has got his daughter from previous marriage to turn against me and is taking it on my unborn child saying that his daughter will always be number 1 and stuff which is causing more problems