So I need some advise long story short my partners grandma put a wedge in our relationship by going…

So I need some advise long story short my partners grandma put a wedge in our relationship by going threw our stuff finding my personal journal reading it, sharing it with her husband them making copies and showing it to my partner he knew about so it wasn't a shock to him or anything but now he currently is staying at his grandparents and I'm at mine we've been this was since last Thursday our baby's due in 12 days and to me we're drifting apart he says we're not but last night when I saw him for a bit a girl messaged his phone one I'd never seen before nothing suspicious was said but you could see a conversation was being had but was deleted beforehand and he deleted the one message soon after and I don't really want to be with him anymore not because I don't love him but because we're just drifting apart and I'd rather just cut the cord then have it be a problem down the road