My ex cheated but i dont care?

my ex boyfriend cheated on me, with one of my friends who i have known my whole life. my dad cheated on my mum, and i was the one to discover that he was cheating. but my boyfriend cheating on me didn't effect me at all. i honestly don't even care! he was the one that dumped me if that's relevant. when i found out my dad was cheating on my mum it Absolutely tore me apart. i didn't know what to do, i started self abusing, my trust with everyone and everything was broken and i phoned child line several times, it still effects me now. but now i swear i don't care! why on earth did i care so much when it happened to my mum but when it happened to me didn't care? and yes i do care about him, i care about him a LOT we have gone out before.