Cheater

Hello mommies. 18 years old po ako currently pregnant with my first baby boy at 35 weeks. We have been together ng boyfriend ko for almost 2 years. Nagli-live in na po kami dito sa side nya, as per decision ng parents namin, since nabuntis ako. Everything's going well naman po. Earlier today, I saw a video on his phone. It was him and another girl sa isang motel. It was dated last June 18, 2018. We found out I was pregnant last July 2018. He admitted his mistakes and said sorry naman. As per me, i dont know if I should just let this go since it all happened in the past na or should I make a big deal out of it? Is this a sign na he will do it again in the future even after I gave birth? Help me please :( I dont want to tell this to my parents and friends because they would be biased :(