Did I fuck up?

Boyfriend found an old phone of mine from a long time ago when I was with my ex. Three messages that I sent my ex were of me saying I loved his dick and we were talking about our sex life. My now boyfriend is threatening to break up with me. Called me a hoe and a bitch and dirty. He’s literally flipping out. I swear I forgot I even had the damn phone in my place and if I would’ve remembered would’ve thrown it out a long time ago. I feel awful. How do I fix this? I’ve never talked to my ex behind my boyfriends back, he just really hates my ex because before my ex and I got together my current bf and I were talking and he is the one who broke it off so I got with my ex and stayed with him for two years so that’s why my now bf hates him