She seems to like me, but what should I do?

There's this girl I'm really into at work, and she works in a different department, so I don't see her too often. Back in December I asked if she was seeing anyone and she said she was. That was pretty much it.
For a month or so, she was quiet but friendly when I did see her. But suddenly things hanged and she started to flirt with me. She'd go out of her way to talk to me, or find me. She'd play some games with me, and would get super excited to see me and ignore whoever I was with. If I didn't all to her, she'd get very upset, and she even tried to get my attention when I was in meetings.
A while back, I found out from her manager that her boyfriend worked with her, but she described their relationship as a bad one. One of my colleagues asked the girl about her ring and if it was a promise ring, and she was very dismissive about it.
One time while I was there, I didn't say anything, but she watched me the whole time, and even when walking with her boyfriend, she would glance at me.

Recently she gets very excited and will try very hard to make fully eye contact when she talks to me, and she tries to dismiss that day I saw her with her boyfriend, and says I should have said hi.
Over the past few days, she's come to show she was there and would like bend over in front of me to get something, but didn't actually grab anything. Or exagrate when I said she ignored me. And I'm just confused.

My friend says I didn't actually ask her out and never made a move and I should ask her out for real. But last time I talked to her, a few months ago, she was still in the relationship.
She seems to like me, but what should I do?
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