So my daughter (step-daughter / 18) approaches me with alot of apprehension and tells me that she thinks her mom is having an affair.

She wants to confront her mom. Daughter has had alot of conversations apparently with her dad who seems to have told her that mom my W, was doing this in her first marriage. He told her once a cheater always a cheater. Apparently she was having an affair with someone from work. That lead to various fights and arguments. Her dad ended up running and around and drinking alot. Lead to being an abusive situation. Daughter is real upset and angry at her mother right now. Daughter is real angry at life right now.

She has also talked to her older sister who is also very angry with her mom. Oldest Daughter away at college.

I am real close to both of my daughters (W's daughters).

I have explained to daughter that this an issue between her mother and I. That I ask that she let me handle it.
My daughters are real stubborn and very out spoken. I have always encouraged that. So I am afraid that they will talk to their mom and it won't be exactly pretty.

So what should I do? Let nature take its course?

I am working real hard on becoming detached. I started to move into the other bedroom, but wife told me she wanted me to stay. Wife has told me that she loves me, wants to be with me, enjoys my company, but is very arms length or cold when it comes to being inimate. I feel like she is a roommate.

Very confused!!!!

Desperately need direction, support, advice and help...

It would be very much appreciated. To those who have responded thank you very much... You have been a big help.