That girl started lying when she asked you to hold her purse while she went to the bathroom.
Girls always take their purses with them to the bathroom!
Learn signs of deception. And never have sex with someone who is drunk. There are questions of the ability to consent. You put yourself at risk there.
People don't fall in love at first sight. Keep this in mind, both when evaluating the true feelings of others and your own, as well. What you felt was lust, not love.
And she is a very screwed up young woman, out sleeping with others while she has a boyfriend. She brought her "stuff" along with her and shared it with you and now you've got her "stuff" causing you issues.
In general, "Crazy" parties and picks up other men when she's having trouble in her relationship with no serious intentions for the pick up. Despite professing love, which is really only confused feelings.
This situation could happen with men or women.
So, everybody would do well to keep these types of situations in mind and avoid them.
By the way, you find people when you are not expecting it. You are just moving along in your life, dealing with your stuff as a person, and you meet someone new. You may not even pay much attention to this person at first, but since you know how important it is listen to others in order to learn because people will tell you all kinds of things about their character without saying a word on the subject. And, when they pass that sniff test, and you realize you'd like to see them more, then ask if they would, too. Hang out. See how it goes. Eventually, after some time, you might actually fall in love. See, that's how this whole thing really works.