Back up boyfriend/girlfriend" Would you forgive them ?

"Back up boyfriend/girlfriend" Would you forgive them?

Okay. So I BADLY need an outside, un-bias opinion about this situation. I'm so filled with anger and disgust I doubt I'm thinking clearly.

So I was in a relationship for four years (give or take a couple months) with this guy. Ever since the beginning of things with him there was this girl who was madly in love with him. Just before him I had recently gotten out of a very bad relationship (cheating, verbal abuse, ect.). I had explained to him from the very begining I was still very paranoid, angry and easily made jealous. He promised he was willing to "take care of me" and never hurt me. But as the years went on, things only got worse and worse.

He started paying more attention to the other girl. And I don't mean "Oh. He's talking to her more today than he is with me" or "Oh, he's hanging out with her today instead of me" I mean he literally ignored me. After attempts at trying to get some attention from him by joining in on talking, asking to play video games, things like that(Which is a very big leap for me, I'm very shy and he knows it). I ended up on the other side of the room playing a video game by myself and listening to them joke and laugh together. This wasn't a once in awhile thing. It happened dayly and went on for months. I eventually had a mental break down and refused to talk to him for awhile because I was certain he was about ready to break up with me and go to her.

After a lil' talking, we decided to stay together, but he continued to ignore me (EVEN AFTER I HAD TOLD HIM IT WAS ONE OF THE REASONS I HAD A MENTAL BREAK DOWN). For one year straight I continued to sob and constantly asked myself "Why do I love him?" I never had an answer so I continued to sit there and take him ignoring me (He was also very Intimate with the other girl. They would cuddle, flirt and constantly wed each other on online games as a "joke" He never once even asked if I would like to marry him, "jokingly" or reality wise. I know this because the girl was never shy about telling me about what they did. She would flaunt EVERYTHING intimate she did with him). After the one year I realized I wasn't in love with him anymore and worked up the guts to confess it to him. We have an agreement at the moment that once we sort out our issues we'll get back together.

I talked with the girl recently and she confessed some things to me. (She has no idea we're "broken up", for about a half of a year her and him hadn't been talking to each other ((Argument or something. Don't know the exact details between them))) She believes she had been the "back up girlfriend" for him. "Any time she would find interest in another person, I would disappear or she would try to move on from him, he would pull her back in. Saying things like "if things between us didn't work out he'd probably end up with her" " Her words, not mine. She's shown me conversations (Saved AIM files) of him saying these things.

I have been in a depression state for three of the four years we were together. After the "break up", I was feeling better and have become much happier. To the point I'm pretty sure I want to break things off completely with him and date around. But until I had that talk with her, I wasn't completely sure. I'm now so angry and feel so "toyed with" that I'm about ready to end it completely. Before I do something stupid or over react, again, I need unbias opinions on this situation.

How would you feel? What would you do, in my place? Give him a second chance? Cut ties? Am I over reacting and angry for no reason, or do I have a good reason to at least be a lil' angry?

Is having a backup girlfriend or boyfriend wrong?

I am simply curious what other people think. I am already set on my views. It's just that recently someone that I was dating and recently became "just friends" with (even though it just feels like we're on a break whatever that means) told me that he had "opened communication" with his backup during the 2 weeks we weren't talking to each other. I don't know if he's still talking to that person...

I don't understand the whole concept. It's nice to be realistic, we all go through breakups and it's not fun being alone, but how can you fully be committed to the relationship you're in (whether you're dating or anything more serious) when you have an escape route already planned?

Later later
At this point we're not in an exclusive relationship, so even though I think backups are wrong and he spoke to his "backup" I don't think I can really condemn him for it. He has told me in the past that I'm the only person that he wants to be with and that he's willing to be friends with the hopes that we'll become more than friends later. I had changed our relationship to "just friends" but then realized that I just wanted a little space and was starting to make efforts to see if we should start dating again if he was ok with it, but then he mentions his backup. I'm wondering now if he's just trying to make me jealous or hurt my feelings... (he's done a few other things to make me think so)