My (F18) boyfriend (M18) hid my ex boyfriend was cheating on me before we got together. Should I confront him?

Title sounds very complicated I know. My (F18) boyfriend (M18) is great and all. He has great morals (for the most part) and is very trustworthy. However, I will say that we’re mainly friends / now dating, because my previous boyfriend was his best friend (emphasis on the was now that he’s dating me). My ex was awful to me and that led to a lot of his friends ditching him and me eventually breaking up with him, although I always justified his actions at the start. I wont go into detail, but he yelled at me often and took out his anger on me and then also coerced me into sexual activity and pressured me until I gave in a lot.

Anyway, I probably would’ve left the relationship far earlier if I knew then what I knew now. A month after I left him (my feelings were sort of gone ages before because of what he put me through), my boyfriend tells me “yeah (ex) was having dreams about (his ex talking stage of 5 years) while you were together.” And it felt like my whole world stopped. Not because I had feelings for my ex, but because I had gone 1.5 years and no one had mentioned this to me whatsoever. Then, my BF brings up that he was also talking to her again a few months before the break up and was agreeing to hang out with her, etc. I heard about the contents of some of the dreams… it wasn’t very PG. I found out these dreams were going on the whole time - the first one was 10 days after we got together.

I feel heartbroken but not because my ex cheated on me. I’m disappointed I wasted all that time sure, but I’m devastated one of my best friends could keep that from me. He said to me at the time that he was scared I’d have a breakdown or kms if he told me, which I thought was a bit extreme. He said there was already a lot going on and didn’t want to make everything worse.

A few weeks after hearing this information and I’m still upset at him, but I don’t want to seem like I’m beating a dead bush or I’m obsessing over an ex. I’m more upset at him for not telling me now and it makes me wonder what else he could hide from me. I feel like if he was just a friend still I would’ve cut him off for this.

Am I valid for feeling this way or should I just move on? If my feelings are valid on the matter, would it be wise for me to confront him again and how?

TLDR: my boyfriend lied to me for 1.5 years I was being emotionally cheated on by his old best friend (my ex). Can I confront him?