How do I tell my friend I have been masking for 5 years?

I have a classmate, who doesn’t know who I really am, because I’m scared of talking near my class since some of them make fun of me, so my friend thinks I’m super shy and quiet, when I’m the complete opposite outside of school. I have had a crush on her so I want to be more close but I don’t know how to naturally make it seem like I haven’t been lying to her a lot. It would be nice to tell her but I think that it would be weird since we have been talking less and less over the years, but I really really want to try to get closer. I’m also really bad at small talk. I can’t talk to her during school, since she is popular so constant surrounded. What should I do? (I have snapchat and other places where to contact her online btw)