How am I supposed to feel when the other guy is ugly?

I don't want to sound rude, but the other guy is very unattractive. And I'm not saying it because he's the other guy or whatever. He is objectively very unattractive.

Has an unkempt beard, is overweight, alcoholic, smoker, stoner and apparently games for 12 hours plus a day.

I know a bit about him because my ex and he were friends throughout our entire relationship, and she'd try to set him up with her female friends and they'd always reject him.

He has only had 1 gf, that too in middle school. And my gf was his first kiss (they made out when she cheated).

Albeit our relationship was going through a rough patch when she cheated, and we were almost broken up, I cannot help but compare myself.

I'm not brad pitt but I take good care of myself. I don't drink or smoke. I cook my meals and only have healthy food. I'm well dressed and charming. I didn't do weed and work hard at whatever I do.

I don't want to toot my own horn but I get hit on often. Have slept with 8 girls since my break up 3 ish months ago. Girls like me and so do my guy friends. My company in enjoyable and I'm always getting invited to some party or the other.

As far as I know, my ex hasn't spoken to the guy since the break up, or gone to meet him, or wants to do anything with him. (Ex and I have mutual friends who informed me)

When ex and I tried to reconcile, she said the other guy is very unattractive, smelled and was a disaster at kissing. She said she was drunk and wasn't thinking, plus the stress of our almost break up made her do something so reckless.

I don't know how I'm supposed to feel about this. Am I lacking in something that made her cheat with some lowly guy who can't get a girlfriend to save his life? He's a virgin and has no female friends.

How can I stop comparing myself to him?

In a way, my promiscuity is influenced by the fact that I feel like I'm one-upping him. If that makes sense. He barely has held hands with a girl while I've been with 8 women. And the number keeps going up because I feel horrible unless I find a nice girl who's attracted to me and wants to have sex with me.