Can anyone give me some reassurance

I dated this guy who was so bad to me, I never felt confident or beautiful all he ever did was tear me down and make me insecure. He ended things with me and I was still heart broken. Everyone says I should be over him because he was so horrible and I know this is going to sound stupid please don’t laugh but someone took his place as my best friend on snap chat and I was a moment that like made everything feel real (cause my ex has been my bestfriend for over a year now) I couldn’t help but feel guilty for a new super nice guy taking his place? Should I feel guilty? Idk this all just sucks and it’s caused me to stop talking to this new really nice guy just cause of how in shock I am