Search Results: boyfriend flirt with my girl friends

Been seeing this girl on and off (no label). Kind of a complicated situation. I'm 27, she's 20, with a really protective family and a lot of older siblings. Seems like during a 2 month period she was back in her country, we weren't together but texting, she got a "boyfriend". I didn't know until one night we were hanging out recently, her little sister said something like "insert name, misses her boyfriend". I said "what, you've got a boyfriend?" and she looked at the sister angry and said to me "no" twice. The younger one wanted to put me on her Instagram live and the girl gave her a death stare.. which now makes sense because she didn't want the boyfriend in the other country to see she was out with me at a bar at 1am. The boyfriend looks like a spotty 17 year old, so I don't know if it's like one of those weird texting kid relationship things. The other night the girl said to me "in this relationship" about me and her, and I thought she was hinting.

The next night after she denied having a boyfriend, her guy friend the same age asked her in front of me "so how's your boyfriend back home". The girl tried to divert attention but was drunk and ended up telling him "he's a good guy" this is his name etc. The same night she was walking down the street and holding my hand and flirting hard.

She knew I was mad, I went silent and cut the night short, said I was tired and took her home. Her face looked worried like I could cut her off. She text me the next day to break the ice and I was cold, but didn't say anything. I text her tonight, she said she knew I was annoyed, but I think she thinks it was because I was jealous she flirted with the friend (which I was). Quick replies between us, and then in short I said "you told me one night you didn't have a boyfriend, then the next night you were talking about a boyfriend back home to your friend". So you're either confused, don't know what you want or lied. She left it on read, but would have read it on her home screen.

I asked out this girl a while back, and she politely declined, and told me she had a boyfriend.
Since then, whenever I see her around, she's always incredibly nice to me. It's come off as flirting, and I thought I was seeing what I wanted.
But I know who her boyfriend is now and although I know they've been having problems through mutual friends, she's become very flirtatious 2ith me.
Our mutual friends have noticed and brought it up to me. Suggesting I'm a backup or bait on the hook if things end. She's not like that with anyone else or even her boyfriend.
But I feel like I'm being teased. If she likes me and isn't happy why not break up with him?
My friend told me if I directly talk to her about it. It gives her power and lets her know I'm wrapped around her finger.

What should I do?