SC: I never wanted to be in this position, I wanted to be happily married for life. But since I am, I kind of feel like this might be my last chance to move on if I have to and find someone who really likes ME. If I ride this rollercoaster for another 2-3-5 years, I will be an emotional mess, older, financially insecure, and then what? But I so don't want to live on my own and date either. I want my old life back, or what I thought it was!
This is what you need to think about. If you really think he is only offering you a few years before he acts like this again, you might want to move on.
You will never have a guarantee that he won't do this again. Life has no guarantees.
Also, you would HAVE to date him (without kids knowing?) for you to find out if you even want to take the chance. Are you willing to try it for three months? Would that make you unable to get out of it in any way or set you back too much? Maybe you should not look at "trying" as "promising him 2 years." More like "trying for three months." You DO NOT HAVE TO TELL HIM this trying is on a trial basis. Believe me, YOU are on a trial basis with him, so you would not HAVE to point out or share your own point of view about this.