Would you forgive a cheater

The reason I’m asking is, my boyfriend and I started dating in oct 2016. A few weeks after we started dating, he got really drunk and went to his exes house, and ended up sleeping with her. This crushed me. But I knew him enough to know he was trying to self destruct, and not fall for me and maybe get hurt , he never put himself out there to actually love someone. the fact was we weren’t extremely serious yet, so I chose to forgive him . But even after all this time, it’s in the back of my mind like “omg this actually happened and it scares me and it hurt like hell to deal with.” But we now live together and I love him so much and I trust him. But it still hurts to think about that time , look at the pictures from then , everything .