My bf (17M) cheated on me (17F). Any advice to move on?

My bf went abroad during this summer and cheated on me. Only reason I found out was because the girl he did it with messaged me first. He basically removed my user and our pfp together from his instagram claiming that he didn’t think convos about relationships were worth his time at this summer camp. I thought that was absolutely bullshit and had a gut feelings. As it turns out, my gut was right and I got the hey girly message after he posted me on his story for gf day. This was about when the girl also told me he went around bragging that he had a double digit body count, was horny, and was looking for a girl to have fun with. I js immediately dumped him after almost 6 months together but I genuinely can’t wrap my head around what happened. It took me two days to start crying which only lasted for about a minute and now I just feel so empty. Then I hear that he told people he didn’t even care abt me because he got too much motion at his camp. I feel so stupid for liking someone like him and I simultaneously miss him so much. I really thought we were doing well. This just hurts a lot because it’s my first relationship whereas I’m his third. I wasn’t aware that his past such as his body count was like that. Despite all this, I miss him but not to the point I cry. Still, I’ve lost so much motivation to do anything and feel so lost. I was mentally tired before and this relationship genuinely healed me until it didn’t. Any advice on how I can work on myself? Maybe niche advice other than focusing on myself😭