I love her....

So I’ll start from the beginning. I was dating this girl for awhile and after a month I started to fall in love with another girl who flirted with me and I flirted back and it was fun. I never cheated but I did want to hide the fact that I had a girlfriend but she knew (btw in high school so she just saw us around the campus) anyway fast forward to the end of the school year last year my girlfriend had cheated on me and throughout are relationship she was very emotionally unstable and told me very weird stories frequently(she’d tell me a family member of hers tried to kill themselves or was murdered like every week it was insane) so I was looking for a way out thankfully she cheated on me and I used that to leave her. Flash forward I’ve started talking to the girl I fell in love with again so my question is what should I do? She has a boyfriend and they’ve been together for 11 months should I wait it out and see if they break up or best to move on with my life?