Need advice

So I found out that my partner is cheating on me. A mutual friend of mine found my partner on tinder. Mind you I’m like 8 months pregnant right now. I’m definitely planning to leave him. Should I just pack my things and leave or should I confront him. I just don’t want part of him if he’s willing to go look for someone else while I’m about to have his child. It’s heart breaking and a slap in the face to me. I just found out about it.