I Was That Kid Who Made Fun Of Someone's Handwriting

It was last week when we had our big spelling test. The teacher told us to write neatly and clearly so she could read our answers, but I don't really like handwriting anyway, mine always looks messy. So, I thought it would be a good idea to make fun of my friend Sarah's handwriting in front of the whole class because it was really messy and hard to read. After the test, I showed everyone how bad her letters looked, making them all giggle and laugh at her poor spelling too. I know that wasn't very nice of me and Sarah told me she felt hurt by what I did. My mom says you shouldn’t point out people’s differences like that, but I still feel like it was funny at the time because other kids laughed with me instead of just being mean. Now I’m wondering why I thought it was okay to do this. Did I really think making fun of someone's handwriting would make me more popular or something? Maybe I should have been nicer and helped her practice her writing after class instead of laughing at how bad it looked, even though I struggle with neat handwriting too sometimes. But then again, why would she want to spend time with me if she knew I was just going to laugh about things like that? Now I feel guilty but also confused because making fun of someone felt kind of good in the moment. I'm not sure what's wrong with me or how I can make it better. Should I apologize, even though it feels weird and embarrassing? What if she says no? Would that mean we're still friends anyway? All this thinking about why I did something mean is making my head hurt.