Best way to move on from last fuckbuddy?

I cut it off with a guy I was sleeping with a while ago because I found potential evidence that I was just his side girl & that he might still have a girlfriend. He added me on all fake social media accounts & lied to me & said he 'doesn't have' a real instagram but I did a bit of stalking based on some things he told me about himself, & I found his real social media accounts & found that there were comments & love reactions to his photos on Facebook from a girl, which were from about a year before I met him on tinder. I haven't found any other direct proof of them being together after that or during the time I was seeing him, but I noticed he was still following her best friend and her sister, and the girl herself was & is still following the barbershop that the guy owns & works at, & likes nearly every photo that he's in, so I assume they must've still been together during the time I was seeing him.

One day I requested to follow his real instagram to see how he'd react & he let me follow him, followed me back & then blocked me 3 days later, which means he was uncomfortable with me seeing his account. During the 3 days I was following him, I noticed he was still following that girl, & she had liked his recent picture, so it's likely they would've still been together. Even though I've made the healthy & correct decision to cut him off, I'm really struggling to get over him as I had very strong chemistry & romantic feelings for him over the 1.5 years we saw each other. Whether or not he was telling the truth, he used to tell me he had feelings for me & wanted to date me but that distance was a barrier at the time, but now we both live in the same city & he finally admitted that he just wanted to have fun with me & is 'not looking for anything serious', so that really ruined things for me knowing he was lying before & just playing around with me, whilst he considers his girlfriend & other girls more important. It's shit knowing that I'm so worthless to him.
Best way to move on from last fuckbuddy?
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