If your wife is in MLC, then you need to slow down, and take a breath or 10...the infidelity advice is different in the MLC area because there are different motivations and such at play.
Cadet should be around with a welcome post and CRITICAL info links.
You have a child, so this is your most important consideration...what effect will my actions or decisions (kick W out, or not, etc) have on him?
Don't act on this right now...read DR/DB, learn all your can about MLC first. Foremost, work on you and be the best father to your son, he needs YOU 150% there for him right now.
Sorry you are here, welcome to the jungle of mlc, you have some great people here to help you!
T^2
In the depths of winter, I finally learned that within me there lay an invincible summer. - Albert Camus
Uncertainty is the very condition which impels people to unfold their powers.-Eric Fromm