I need advice !!!

Last night my boyfriend and I went to a family party last night and we got a little drunk and obviously had sex last night. I’ve been with this guy for a year and a half already. We live together. I remember we took a video so I wanted to watch it. We have each other’s passwords and everything. I end up finding a video of him bouncing on a dildo up his butt! I’m so in shock right now because he was always squirming if I teased him around his butt to be funny. He always told me that and whoever else his back door is a no. To find that…… Idk but I tried too to see maybe is he cheating on me so far nothing is found. Idk if this is just me but that’s a huge red flag 🚩 what do you think????