Is it wrong to hookup with a guy your ex HATED?(like REALLY HATED) ?

Ok, so just a bit of background. Technically I did have a thing with the 1st guy before me and my ex dated. But he (ex) HATES him (1st) so bad.

Me and my ex broke up on good terms. Tho we do not keep in touch and have both (kinda) moved on.

I feel kinda guilty but at the same time, it's not like am getting back with my ex.

So guys and girls, is it wrong?
Is it wrong to hookup with a guy your ex HATED?(like REALLY HATED) ?
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