My fiancé and me are close to separating help😩

Jennifer • Been ttc #1 for 4 years my fiancé is 32 and I`m 32 will be going for IUI soon 😊
My fiancé is 32 and so am I we have been together on and off for 20yrs he has slept with 2 other girls plus me. And I have only been with him. But I'm fine with that it was my decision. Recently he has become very cold and distant he says he is only staying with me cause he feels sorry for me but then he tells me he loves me still but needs his space. I have been reading some old texts from us and I realized that I have been smothering him I'm so needy I make myself sick and all the pressure I put on him for a baby it's insane. We have been trying for 4yrs and I really believe it has torn us apart now. I still love him so much I don't want to give up on us plz anyone have any advice or has been in a similar situation? I'm so 💔