Cheating Boyfriend

How do you get through feelings of wanting to seek revenge? My ex bf and i broke up 3 weeks ago because i accused him of cheating. So i decided to go drop off his belongings on my way home since i had to pass his house. He ended up having his best friend in his bed...exactly who i accused him of cheating on me with. We talked for three hours and Then he asked for a fresh start with the new year and everything and I told him I would consider but some things would have to change. He ended up asking me a question regarding how he makes me feel and i answered honestly. Next thing i knew he was livid and cursing me out. All I said is that I don’t always feel special to him. So since then he has completely ghosted me. He still watches my social media stories and accounts but has not reached out. I found out that he is now seeing another girl who drove 5 hours to stay with him for a few days. I feel so low and just hurt because we planned a future together and now i don’t know what to believe. How could he move on from me so fast. Did he ever mean what he said and love me? Every holiday we spent together, birthdays, trips... I’ve been there through everything for him. I have a key to his place. Nothing makes sense but I’m fighting the urge to let the girl know everything but I really want to but I know deep down that won’t do anything. Idk what to do or how to feel.