Cheating is the involvement of another party, whether it is physical or mental.
Someone else on the board mentioned that if your spouse isn't a part of it or you don't want your spouse involved--it's cheating. Geez, it's cheating WITH a 3rd party no matter how you view it.
The bond with your spouse is just that, a bond. It's a bond emotionally, spiritually, and physically. Cybersex excludes your spouse. If you have fantasies, get your spouse involved. Most would be surprised how willing spouses are to enjoy their mate's fantasies.
I'd suggest you enrich your life with your real-life partner rather than clicking at the keyboard keeping a wad of kleenex handy. For those who feel the need to resort to such, that's very sad.
Congrats to Montana who stood her ground. Like you Montana, I hope the wife of the former-friend found the wherewithal to make a new life for herself, she certainly has been underappreciated and deserves more out of life.