My girlfriend's ex is way better than me, how can I feel better about myself?

Anonymous
I have no clue why, and I know I'm so stupid to ask my girlfriend, but I asked her if she's been with someone with a bigger penis/more attractive and she said yes. She's been with 5 other guys, I can't stop thinking how much better they were and I'm all self conscious. So now I feel like shit and was just wondering if anyone could give advice, thanks in advance.
My girlfriend's ex is way better than me, how can I feel better about myself?
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