Has she been using me to make her ex boyfriend jealous?

I've been seeing this girl for about four months now. Recently I discovered that when she went to her home town she would stay with her ex, I also found out that almost every time they were together they slept with each other. She says that she was very drunk and that she couldn't remember what happened until the morning after. I forgave her because of those mitigating circumstances and because I think I love her. Her ex was the one who told me, he is still very much after her and he hates me. This weekend she is back up in her home town and she's been staying with her Ex. Extra info. Also when I text her I can perhaps get a response in about an hour. If he texts her she replies almost instantly. She was seeing her ex for about two and a half years and they were best friends for a long time. He keeps intentionally hurting her emotionally in really cruel ways. but she keeps forgiving him. They broke up seven months ago after he seriously let her down and did not contact her when she was very ill and in hospital. Should add that we do spend a lot of time together and she does say that she loves being with me. I'm just unsure whether those words are as hollow as the ones she said to me on one of the nights she slept with him. But she does keep saying that she wants to be with me and that those times were accidents. Any advice? Also, I've no way to contact her just now other than email until Tuesday. Should I ask her like that or wait till I see her?

I think you are right. She is. Walk away and find someone else.