Anxiety hindering my love life?

I am 17 and have been diagnosed a year ago with OCD. For those of you who don't know, OCD in a nutshell is an anxiety disorder where a person has intrusive and disturbing thoughts, that are allayed by compulsions (everyone thinks of hand washing, but for me a common compulsion is checking my hair and making sure it is perfect, otherwise I feel as if something bad will happen. I have gone through a lot of therapy and have come a very long way. I am becoming a much more confident, happy, and independent individual. There is a girl that I have had a crush on for a few months now. The problem is that she is one of my ex's close friends. A girl told me that when I broke up with my ex, the girl I currently like kept talking about how sad it was that me and my girlfriend broke up. She said that I was cute and funny. That happened about a year ago. We hang out in the same group of friends occasionally, but we go to different schools. Most of the time we communicate through texting. She seems to give thorough and thoughtful responses when we text, however she won't ever respond immediately. Typically we have about and hour between each text we send. I'm picking up the vibe that she likes me, but I'm not positive. I have flirted with her pretty blatantly over text, and she continues to talk to me. Things haven't really gone anywhere with us but I want them to. My dilemma is whether to ask her out, and if so, how? We don't know each other super well, so I feel like it might be too soon before she knows me well enough. Also, I think she might tell me she isn't interested in me just because I'm her friend's ex. I was thinking it might be best to keep things slow and not do anything. The other option is to tell her I like her, but to not ask her out. Any advice? If I end up telling her I like her should I do it in person ?