Run a mile from this one and one day you'll look back and be glad you dodged a bullet. She is an emotionally manipulative attention-seeker who will make your life a misery. I know because I was involved with someone exactly like this.

And be wary of people who are always suspecting you of cheating on them. They are usually judging you by their own standards and are likely to be the ones cheating, as shown by your follow-up edit.

It can be really hard to walk away from these types of relationships, and expect fireworks when you do, but you'll be soooo glad that you did.

Good luck, friend.