
Not to that extreme but I know what it's like to be in your shoes. I don't know that there is anything else that you can actually 'do' at this point that you aren't already doing. You need to follow through with the promises that you have made already. Luckily this was just the first contact, was it innocent or did you tell him you missed him or something? I would get rid of facebook, I would not let him be a friend on there, I would delete and get rid of every method of contact you have possible. It's hard to cut ties like that (even if they don't know) but you need to throw/burn everything out.
Since you have a marriage counselor, I assume you have explored what feelings are driving you to contact this person in the first place. There has to be void that you are filling that causes you to want to reach out to this person. That is the void and feelings that you need to examine. Why did you message him last night? What feelings caused you to do that? Some people like drama, some people need to feel needed ... every person that has gone through our lives gives us something that the others don't. What is the hold this guy has? What has he done? You can do anything to try and save your marriage right now but if you don't address the underlying issue to why you are reaching out to this guy, things won't get much better in the long term.
Good Luck .... this is going to be a tough time for you guys .... It's harder to face the truth about why you are doing this than to just move past it and reprove you are trust-worthy.