Two of hearts..... repeat behaviors of anything resembling active addiction are always difficult.
On the Face Book part..... I am not so much a face book user.... but I do use Myspace. My guy has a myspace, but doesn't use it. He often wonders why he even has one. Now.... if it were me and he was up in my personal business... regarding lets say myspace... it would drive me bonkers. However, in my codie ways I can be all up in his business?? So that is when I stop and look at myself. The best advice I can give you is that you pay the most attention and give weight to how he is when he is with you and around you. This also helps with the snooping aspect of things..... ya know? I'm not saying that is what you are doing, but the FBI or Nancy Drew syndrome can get the best of us.
Trust is so hard to re-build. I know this..... we all know this.
Are you going to al-anon groups? Are you both doing the recovery with f2f ESH? This is what has helped my guy and myself SO much!