dealing with a mono/poly relationship

Well I guess I'll start at the beginning:
Almost 2 years ago I started dating this guy i was pretty into, and we both agreed that we'd be non-exclusive and date other people (I had no idea until recently he was polyamorous or what that meant). I was fine with it (he was even sort of dating someone when we got together) but then it turned into a relationship and I fell in love with him. When it comes to love I'm really monogamous but he isn't.

Now: I'm struggling with this idea and concept. I love him and want him to be happy, but I also want to be happy. We've been fighting a lot, and we have both lost some respect for each other. I've been hurt a lot recently with his actions with other girls. I've felt pain, anger, abandonment, betrayal and fear. I know nothing of what polyamory is, the first I've even heard of it was recently from a friend of ours. So now I'm looking into it, trying to figure out how to deal with a poly person and get the view point of others in this type of relationship and how other monos deal with their partner being poly.

What now: We're currently on break so we can try to figure things out. I guess we both need to come up with a list of what we need and try to come up with rules and compromises. I've joined a few forums and support groups and have learned a lot. It may even be possible for us to both be happy in this relationship. Anyway, I'm going to be posting our progress in hopes to help other people like me, because I've had a lot of help from others in similar situations in the past few days.