I'm separated serveral years because a woman friend of my wife's became, to me at least, an affair. It has all the attributes of an affair, except for known physical expression, but lot's of hugginess, etc... It's maybe too complex to go into in depth, but she said this woman loved her and I didn't, and letters to one another had statements like, "our relationship is coming to completion". Significant is the abandonment of our marriage, but also the vlifiying of me to justify it. It seemed she was trying on several occaisions to "break up" with this women. There is no end to what she will say or do to make it seem she was justified, but the things she says I don't take ownership of, but she sees it that way anyway, but it seems only to justify herself, she's doesn't seem to want me to change, just have the reasons for leaving. I've taken these things seriously, until I realized it was everything. I've been destroyed personally.
To be very blunt, and I can do this online, towards the end she insulted, if not assaulted me sexually. After consentual sex, she walked out the door saying "what's the big deal about something so small." Now in defense of myself, I'm average. But I'd never approached my wife any way but considerately, and have been the recipient of many fine compliments over the years as to our lovemaking, and consider myself an attentive and passionate lover. and if she wasn't interested, I was able to go watch tv or chill. but does this sound like a lesbian attitude? Her life at this point is pivoting around this woman. Also, she had lost interest to a large degree, except when she was with this woman, and would return home surprisingly turned on. I realized the contrast right away, it was like a consolation prize.
Our life unraveled in many many ways around this issue, I shared this because I think sex is an intimate area, and my being was assaulted in this way. I struggle now with pornography as my self esteem is beat up, and may be tempted to regain my "manhood" some other way. She also ripped into my fatherhood, my career, alienates me from my kids, holds to a spiritual self righteousness. We have 8 kids together, and no one can process this, I live each day trying to go on without knowing why.
It seems the marriage is over. But I can appreciate any feedback on this.

well it's only over if you want it to be.

Have you done any reading in the FAQ section of this site?

It's an affair BTW.

Have you exposed this affair to anyone?

Why is she alienating you from your kids. How does she have this power?

Yes, it is an affair. Yes, you have a right to be suspicious.

Put spyware on the computer and read her emails. This will likely give you the ammo you need. DO NOT reveal your evidence to her right away. Come here and talk about it and get advice before confronting her.

I'm sorry you're going through this. Start documenting the heck out of everything and take steps to protect your kids. You'll really tick her off when you block her financially but the answer is always, "You can get a job and pay yourself for your cell/car/outings. I will not fund immoral behavior. You can have all spouse priveleges and trust when you earn them back."