Please help idk what to do I'm hurt but can't seem to leave

Dana
Hi my
Fiancé for 2 years has secretly
Hid online sexual role playing with other woman of consent age up
Till cougar aged on an app on his phone he's done it about 4-5
Times alone on that and now he's on Craigslist sexually role playing with woman it's hurtful and upsetting I've been with this man for 4 years and we have a son due in June idk what to do I can't bring myself to leave but I told him
If he does it again it's the last time he will do it to me because I'll leave idk what to do though I've tried so hard to do what's best for me and our son but I've realized that when he's here in June him doing it will only
Make things worse