Are there people that just live for the affair and nothing more?
How can you know who you are dealing with? Someone worth the effort or someone that craves the next new thing

I'm probably not the ideal person to answer this question, considering I fall under your category of "habitual cheater." i just posted a discussion called "Sex addict or cheater?"

I will tell you that 10 years ago, I cheated the first time. It lasted about three weeks and I stopped. I confessed to my husband of my own accord. 6 years later, I cheated again, this time with a few different guys over the course of a year. He found out from a relative. I started going to counseling, thought I was getting better, and just three months later, did it again. Finally got back with H, then two years later cheated again. It was a 2 week A and I realized really fast, after the very first time I was intimate with the OM, that I didn't want to go back down this road again. I cut it off, came to my H and told him I was "about" to have an A and told him I was sorry. I finally (just last week) told him the real truth about what actually happened then. (that was over 9 months ago)

I am a great wife when I stay focused on the family, but when I look in another direction, I get side tracked. Am I worth keeping? Well, H seems to think so. I cook, clean, I am funny, I am a singer, actor, and dancer, good to my husband, an excellent mom, we laugh all the time, I rub his back, etc. All the things most men want in a wife.

I have a problem. I feel like I won't do it again, because this time I stopped the A of my own accord and went to hubby to stop myself from going further and I also confessed later without being caught or forced to. I see that I am getting better and making progress and I am deffinately going back to counseling, but who's to say rather I am "worth" staying with? I guess it depends on the BS and what they are willing to take and what I have to offer during the great times that might help him better deal with the hard times.

Now please don't misunderstand me here. I am not bragging; I'm quite ashamed of my behavior and when it happens, I realize how much it hurts my H and how he doesn't deserve it, but to answer your question, I had to explain that I am what you might call a habitual cheater, but I am making progress and how do you know when enough is enough? Well for everyone the answer is different, but I am more than eternally gratefull for a spouse who has compassion, patience, and forgiveness that far exceeds normal human nature.

mismindles, as an actor and dancer you have many opportunities to cheat. You work in an atmosphere where cheating is winked at, accepted and expected as part of the lifestyle.
You would benefit from reading about marital boundaries--how to protect your marriage as you relate to members of the opposite sex, ie not flirting or talking sexually, not engaging in private personal conversation, not attending parties without spouse, etc.
Habitual cheaters have lots of problems but looking at your boundaries would be a good place to start the growth process.