Before we got married she was very sexually adventurous. She has had a threesome and been with two black men, as well as about 15 other men by the age of 18 (that I can get her to admit to). Once we got married we had sex 2-3 times a day and had a lot of fun experimenting with toys and anal. But now that we have been married for eight years, she has lost interest in sex but will give me the occasional pity *******.
She flirts with a friend of ours son, who is her age. My wife always wants to spend time with this guy, whenever he is visiting my wife will say "who wants to go to to the store with me" and its obviously an invitation for the guy to go with her. One time they went to the store to get a couple of things and took over an hour and when I called no one would pick up their phone.
I am suspicious of this behavior, and I have confronted her about it, only to have her emotionally explode on me first with anger and defensiveness and then with tears. She denied there being anything sexual in nature between them but the flirting is obvious. They play punch each other and are always smiling and laughing together in a Jr. High romance kind of way.
Also last year she told me that she wanted to go to the adult store, so I said ok and she started looking at dildos. She ended up getting a really big realistic one called Adams cock pleasureskin dildo. So now we never have sex but she claims that she never uses the dildo.

What is up with her behavior? I feel like she is cheating on me but have no proof and if I confront her and try to bring up the subject she totally flies off the handle. I feel like going elsewhere for attention just as she has with her "friend" what do I do? Please help