I began dating my current girlfriend in December of 2007, but she was, at the time, on a "break" with her ex. I of course didn't know this until later but everything was fine. Then in February she told me that she still had feelings for him. We pushed through everything but her feelings didn't go away. Then in April she broke up with me and started going over to her ex's house and fooling around with him and such. Eventually she decided that she wanted to be with me and we got back together. She tells me that she doesn't have feelings for him anymore but I can't help but to not believe her. Now this guy is starting to call her and text her constantly. I am not okay with this in the least because of what happened two months ago and I asked her not to talk to him. She said she sympathizes with me but she won't stop talking to him. I can't help but think that the reason she won't put him out of her life is that she still has feelings for him. I cannot keep going through my relationship paranoid that she'll get back with him so I gave her an ultimatum. I told her to choose talking to him or being with me and she just got mad that I would make her make a decision like that. Am I being unreasonable considering everything that's happened in the past? If so what should I do, just give in and let her talk to him leaving me open to yet another heartbreak? If I'm not being unreasonable, how do I get her to see my side and realize that I can't be with her if she continues to refuse to put him out of her life?

You are not being unreasonable at all... You gave her the chance when you let her come back into your life, but know she is disrespecting you by talking to him still. It is not fair to you and I don't think you should put up with it. I know it would hurt buddy but I think the best thing to do is leave her if she doesn't stop, and if she realizes that she made a mistake it would be up to you whether you wanted to give her another chance.

This is no way to be in a relationship, she is obviously not over him, and you deserve better than this.

I'll just say this straight out, but what were you thinking, knowing the female that dumped you for someone else, is even worth taking back? Now she is still sniffing around him, and he around her? NO WAY!

You don't give her an ultimatium, you give her the boot, and no conversation. Then at least you can salvage some dignity out of this.

She used you as the Rebound guy first time around and then dumps you. She goes back to the Ex and probably realises it wasn't all that rosy anyway.

Now she takes you back and by you letting her , she knows you will be at her beckon call whenever she needs you , and she will keep doing so while you allow it.

You've given her the ultimatum and she hasn't taken it , doesn't sound to me like she respects your relationship. I'm not normally an advocate for telling people to give up on their relationship but I would dump her before she dumps you again and you lose all your dignity.

I agree with Tal, give her the boot. You knew she had feelings for this guy while you dated, which was the first red flag but you stuck around. She broke up with you(SUPRISE) and then started hooking up with the ex again(SUPRISE) Then she comes back and you welcome her with open arms, if you like being walked all over, then by all means, stay with her.