What's that saying "you're only paranoid because they're out to get you" ?
I don't know what's up with your SIL, but if any of my brothers-in-law started to rub my neck, I would be totally shocked!! That is not very normal, even in a friendly family IMO.
I think you have every reason to be concerned. Frankly, counseling only works if BOTH people in a marriage are truly committed to solving the problem long-term. You talked about how counseling helped YOU to forgive your husband- but what did it really do for him?
If he is acting the same way he did before, I would not be surprised if he has reverted back to his old behavior. I think you should make him return to counseling with you and confront him about his change in behavior and his returning to old habits. If he says you are too suspicious, remind him that he has given you good cause to be.
Seriously, if he is not really interested in changing permanently, then all the counseling in the world doesn't matter. If he is cheating again, you have to decide if you will put up with it or not.
I am so sorry you're going through this! My ex didn't cheat on me, but he was a habitual, compulsive liar and we went through tons of counseling. He said all the right things in the therapist's office and changed his ways for a while- then gradually reverted back to his old ways, worse than ever.
Confront him and get to the bottom of what's going on. If he is cheating, or even thinking about doing it again then HE is the one who has a problem he is unwilling to fix, not you. If being married is not really the lifestyle he wants, then the best thing you can do is face reality, however painful, and figure out how to move on with your life. Good luck!!