Hi and welcome to the SSM forum. I'm glad to see that you have both read SSM and are willing to give your M another chance.
To come clean or not come clean; that is the question that I have struggled to answer myself. For now I have decided for it to remain a secret/in the past. You can read my thread for the struggle I had with this question and how I am dealing with it for now. Also some good advice about coming clean or not.
Since you suspect that your huband has had at least one A, maybe he suspects the same of you? I know that my wife at least has a suspision, so at some point we may have to work through the issue of my A's. My thought was if it came up I would not lie about it but if she is choosing to leave it in the past, I can leave it there too.