Boyfriend's crazy ex won't go away

by Frustrated
(USA)

I have been with my boyfriend for the last year and a half. We met about 11 years ago. When we became romantically involved the relationship took off really fast. I guess the fact that we knew each other, and were attracted to each other for so long made it easy. We moved in with each other in less than a month. Over all the relationship is good. Our fast romance is turning into a good partnership. There are some issues, but I have one that I am struggling to overcome...

My ex and I introduced him to his ex of 3 years(she was my ex's best friend in high school). And that is where my problem lies. She is relentless... I cannot for the life of me get her to go or stay away. I completely understand her being upset when we got together even though her and I were never that close of friends. She has always annoyed me, but I was always nice to her because of my ex. She and my boyfriend were always very on again-off again. He was never happy in his relationship with her. When they would break up if he started dating someone else she would start being a creeper until she got him back. I know because I witnessed it, and I really should have expected the following from what I have witnessed in the past...

When my boyfriend and I first got together I did feel a little bad about it. I understood her being hurt, but she has taken hurt to a whole other level. She stalked us for several months, showing up where ever we went out for quite some time... She admitted to someone she would go out specifically looking to see if we were out. She would call the business phone at our work (My boyfriend and I worked together for the first year of our relationship), come looking for him at our work even when I was there (and even though I had my boss bar her because she came in drunk trying to start a fight with us once), when she couldn't figure out a way to get a hold of him she texted MY phone (which was actually only a few months ago). She has also made up lies about me and about him...It goes on and on... And every so often, probably every 3 months or so, she tries to make her presents known in some really awkward way. He chooses the "ignore" route, which obviously has had little effect. I only confronted her a couple of times. I have told her that they do not have children in common, they were never married, and share absolutely no obligations to each other. She has no reason to contact him, and with the given circumstances, her behavior, and the fact he doesn't want to speak to her gives her no right to contact him. She then throws a tantrum, calls me a klepto for "stealing her boyfriend" (that was broken up with her for some time before we started dating), and calls me every name in the book. And then I get infuriated, and mostly because my boyfriend won't do anything about it, expects me not to either, and inevitably it causes us to fight.

I am trying to be respectful to his wishes, but it has been A YEAR AND A HALF! He makes no attempt that I know of to make this stop. It bothers me to point that if I see her in public it gives me anxiety. I just know that after I see her she is going to start getting creepy and stalky again. I have tried to approach my boyfriend about this in so many different ways. Two nights ago I even tried to have a conversation with him about it, explaining to him how much it bothered me and why. His response is, "I understand completely, but there is nothing I can do about it."

It makes me feel resentful towards him. He has absolutely no problem confronting anyone else about anything, but he can't handle this? I don't understand it. If it were one of my ex's behaving like that he would not be accepting of it, why should I have to be? It makes me question whether or not he does still talk to her behind my back. I also have noticed that when I feel like other girls are flirting with him I get unusually irritated and become possessive, which I have never done before. I think it stems from this. I know I am being irrational. I witnessed a lot of what happened in their relationship (she would coming crying about it to my ex and our other mutual friends), and I know he wasn't happy in that relationship. I know that ours is nothing like theirs. I was actually shocked with how different and how committed he is with me... Sometimes I wonder if she is, too, and that is a part of what makes her act like a crazy person. How can I handle this? I can't make him do anything, nor do I want to MAKE him do anything. I also don't want to resent him because of someone who is trying to make that happen. It seems like every time I get over it, she pops her ugly head back up. I have even considered contacting her previous ex and his wife who delt with this similar situation to get some perspective. What can I do to make this end?