Why did my ex changed drastically and became such a hypocrite?

We were together for 2 years on and off in hs we were getting very serious but then he broke up w me over a stupid fight. 2 months later he started going after a girl that slept around w many guys and cheated and he used to say and call her many horrible names. However she did not like him back and now he is dating a girl he used to hate even more and she is an even worst girl with many bad reputations. And she's going away for college soon so they'll b in diff states. I know its not nice for me to say these things but its very true. And i'm just shocked at this drastic and hypocritical change. I feel ashamed for even dated him. also I don't know if this is relevant but we didn't have sex even though he wanted to.
Why did my ex changed drastically and became such a hypocrite?
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