What would you do? Try and save the marriage or divorce??

My husband and I have been together for 10 years and married 6. Theee years ago I caught him cheating.....it was horrible. I decided to stay we worked on us, moved to a different city, whatever. We then found out I was expecting our first child after 6 failed pregnancy’s. Our daughter is now 2 and since then we have had twins who are a little over a year old and I am now 14 weeks pregnant. I just found out that he was having an affair with a 20 year old. He travels for work so him being gone for a few days wasn’t out of the ordinary. He apparently had been seeing her for a few weeks. WHAT DO I DO????