How to not feel guilt for standing up for myself?

[Simone]

I have a friend who always insults me about many things. Ex: my crush, my dream job, my music, etc. So one day she insults me again on Facebook and I lost my temper and told her how I felt. Then she started posting statuses about me but not directly saying my name. I felt guilty after that. I'm not used to expressing my feelings.

Here's some background on me. I am not the type to express my feelings but this time I did. I am a very quiet and shy person, people say I'm sweet and I'm drama free. In the past during middle school, whenever a group of these "friends" started picking on me, I would just let them say crap and not say anything. I would go home crying to my mom about it so she told me that I need to stand up for myself. I did and made them cry and after that I felt guilty.

Now I'm In high school and I stand up for myself and it makes me feel bad. Please give me advice! I always feel like I did something wrong.