Micki I am going through the same thing right now. My girlfriend cheated on me almost a year ago and we are fighting about today. As i type u this, me and my girl are at odds over a bad decision she made 12 months ago. One thing you might have to understand is, he might never get over it, he might never be able to move on. Cheating affects everyone differently. If hes having the mood swings, the ups and downs or the rollercoaster as you call it (I know it well) hes having a very hard time getting the image of you being with another man out of his head. It can be triggered by anything, a song, a thought, a tv show and its all down hill from there. Its not going to be easy and there no quick fix. This is one the karma of cheating. If you want to be with him you have a long and hard road ahead of you, if you can't deal with his reactions to the pain he feels from being cheated on, cut it short and move on.