I know she likes me but she has a boyfriend.

So heres my deal... I dont usually come on here for advice but this time Im kinda stuck and I think she might be stuck also.

So her name is Lisa, and Ive been friends with her for about 2 years give or take a few months. The moment I saw her at work on her first day, I fell for her instantly. So throughout the short 6 months she worked with me, we flirted constantly! It was so obvious! Our eye contact was long and intense with a smile along with it. You know the normal crush flirting stuff. So one day she called me up, it was near Halloween, so she asked me to go to this place called Fear Factory. While walking through, the first thing that scared her she jumped on to me and held my hand throughout the rest of the place and then out to the car. She could have let go but didnt. Well that was over a year ago, and after that every time I asked her to hang out she made excuses that she couldnt hang out blah blah blah. But we still keep in touch. So maybe like 6/7 months ago she invited me over to her new place with her boyfriend to have a few drinks. Well she ended up getting really drunk and I hardly got to see her. Now just this weekend, she invited me over again with her, her boyfriend, her brother and her brothers fiancee. This night she seemed really distant, tried not to make eye contact with me or talk to me that much. Honestly I felt ignored. She got super drunk like usual and she passed out in the bathroom. But throughout the night and the next morning she made weird referrences about gays and lesbians. Her furture sister in law's baby daughter would stick her tongue out alot and she would say "this baby is gonna be a lesbian". Or her sister in law and her were sitting on the couch and for some reason her hand was on lisa's leg and shes like "why are you touching my leg, are you lesbain now?" So now that I think about it, someone wouldnt be mentioning all that gayness if it wasnt on her mind. This is now the next morning, I was laying there listen to the conversations but I was looking at the baby because she was so damn cute. She was sitting on Lisa's lap and Lisa says to me.. "Why are you starring at me?" Its almost like shes paranoid that everyone is going to realize she likes me. So anyways as I was leaving she walked me out and we both gave each other that goodbye long gaze and smile. So that imidiately told me she still likes me and her ignoring me last night wasnt meant to be mean.

I know she has some feeling for me. I know she does, I can feel it! So my questions for all of you are, How do I go about making a move to kiss her?  We have sexual tention and its just a matter of time before we do. But I dont want to freak her out if shes not ready. Also I think she doesnt want to cross that line with me because of her relationship with her boyfriend. She lives with him and has been dating him for 3 years. Plus Im her friend and she doesnt know Im gay. I wasnt out the time her and I met. Now I am with most of the people I work with. So do I cross that line to make a move?

Her mind must be going a mile a minute when Im around. I think the reason she gets so drunk every time Im over is so she doesnt have to deal with what might happen between us. If shes drunk passed out nothing will happen but she still wants me over. I might be her first girl crush and she doesnt know what to do about it. Its a big deal to kiss a girl for the first time and honestly I want to make sure shes ready... or should I just do it because she may never be ready?

All in all I just know she likes me and I need some way of approaching her without scaring her because I know this is her first time.

Thank you all in advance for your advice and opinions!

ps.. sorry for the long post.