wife denies affair so far

We've been married for over 20 years. I do love my wife very much but over the last few weeks she had displayed some odd behavior. She explains things and they seem right to me but I don't know. Here is the wierd part, the thought of her fucking another man is turning me on yet I don't want to tell her that. I go thru my stomach in knots over her questionable nights/days out by herself. I will hightlight them for you.
1. She came home with a different color pantyhose than when she went to work. She said they got a run. Okay can happen but it has happened twice and both times she late coming home from work.
2. Went shopping at the Macy's the last 3 Saturday's, okay woman shop, but she wore make up, heels, nylons, perfume, she said she was going to try on shoes. I asked why so dressed up she replied she was trying on new dresses for Chistmas parties and wanted to look like she would when she goes to them and she doesn't like sticking her feet in used booty nylons. Okay but returned 6 hours later no bags-said she find anything. She did look tired but not disshelved like you guys describe.
3.Goes out with the "girls" now about once a week, always after work and she comes home later and later smelling of alchol. I did check her pantyhose crotch the last two times she came home after she went to relax to see if any evidence showed up. Well there was a lot of stains, some white crusty stains.
I confronted her yet she says I'm crazy. She seems to not have any interest in sex lately as well. I even offered to go down on her last Saturday when she came from "shopping" but she said she was tired and wanted to take a bath and napp. Again her pantyhose crotch was crusty and stained. I have jacked off more in the last 2 months than ever. If she is having an affair I want to know. I don't want to lose her I guess I am wiling to share her.
By the way I decided to follow her shopping today when she goes. I hear her running a bath now.
Funny she kisses me good-bye on Saturday's & Sunday's to go shopping lately so I can watch football. While I'm watching football she getting balled as near as I can tell.
Any thoughts from any of you who have been thru this?

My advice is to enjoy her dirty cum stained panties ,smell for cum.
Go along with her and say to her that you would like someone to have sex with her. Then you might know whats on her mined.
good luck