how to handle these emotions

Coming to the board , after I called for appointment with a doctor,( first ever) they never called back, So im really hoping someone here might be able to offer some suggestions. All the online tests tell me i have both, or a good bit of avoidance personality disorder and schizoid personality disorder. And my life shows it, no friends outside of a few "business" friends. From what i have read, going to work is big undertaking for some, but not for me. No friends outside of work. No social activity , I play games and watch tv all weekend

im going to post something people might take offense at, please be nice.

Im married (meet totally by accident 13 years ago) The sex in the relationship stopped because of medical reasons. I was able to use my hand for 10 years , i held out and stayed faithful for over a decade. Sex stopped while i was in my 30ies. Last year i cracked. I Still love my wife . Posted on craigslist and low and behold, i was actually able that to hold conversations with one woman who responded .All others I couldn’t even write a email to , let alone talk to. Posting was for a NSA relationship. Needless to say my NSA went a little further, feelings were developed. She was in love with another married man in another state. She fell hard for him, but he had a semi reconcile with his wife and moved back home 2 years ago. She waited, no sex, he said a few times he was leaving his wife again but wimped out. They stayed in contact via email. Our relationship was cooking right along, we get along great, the sex is hot & sweaty type, and even better, my social issues seem to almost disappear around her. I actually talk and have conversations when im with her,and other people as long as shes close , which stops after we split ways. Then it happened , she got a plane ticket from him. Its strictly for a weekend romp, THIS WEEKEND. When she told me earlier this week, all my feelings of rejection and the memories of failed attempts of even trying to talk to women , let along pick them up in bars during my single drinking years came rushing back. To put my failures into perspective, from 12th grade to when I started seeing my wife 13 years later, I had no sex, no dates, 1 friend. I have NO experience with relationships. She is my 3rd girlfriend in my life. She has made it clear she wants to resume our relationship when she gets back. We have talked about whats best for her in the past, for her to find a full time boyfriend /husband and drop this guy, the one she loves. I have come to the conclusion I have to drop her when she gets back. Why, because I will continue to have strong feelings for her, and if she ever did find another boyfriend, she would of course drop me. And I would have to go through this hell again.
By her just being way this weekend, going to see a guy she knows who is never going to leave his wife, its KILLING me. Sunday they are meeting up and she basically told me they wont be leaving the hotel room because he can’t end seen with her. He’s in the same hotel with others from his company. Cant do much else but F like rabbits.
This past week has been pure hell, I cant sleep more then 4 hours, while writing my dear kim letter to send later, I kept breaking into tears, my stomach is in knots, im a basket case. Im in bad shape now, Sunday will kill me, they are due to meet up midday. Im basically planning to knock myself out tonight with a sleeping pill. THIS WILLL NOT HELP Sunday day times and Monday morning while im at work and hes getting his last piece. She comes home Monday noon .WHAT CAN I DO? I cant break down crying in front of my wife, but I cant handle this now—Saturday will be worse and Sunday ill be throwing up and crying at the same time while im visualizing this pig doing everything sexual under the sun to her . I CANT CALM DOWN, I have no meds whosoever . I feel like hell, knowing she will be sleeping with him and worst of all, to avoid these feeling from happening again, i must break up with her, by far the best sex i have ever had. And that day next week will most likely be the most painful of my life.