He wants to leave me

We’ve been dating for a while, I’m 25 weeks pregnant and for some reason the discussion of our past came up. He’s been with 1 girl before me, and I’ve been with multiple partners before him. I’ve never cheated nor gave him indication that I would cheat. Yet the conversation came up that I did meet a few men off tinder 6/7 years ago and hooked up with them...which most women did, I’m not the only one. He can’t get over it and said he thought I was different...now all of a sudden I’m this different person to him and he can’t even look at me the same...if he can’t get over this we will have to leave each other ... I’m broken. I’m not who I was back then, I’m a different person, hardworking soon to be mother and I’m being put in the category I was when I was 16/17 young and reckless...what do I do