advice needed...

[CRedskinsRule]

jsarno,
I don't have much advice to offer, I have been through divorce, and been with a woman who had her own kids. What I want to tell you, is that the kids may never understand. The best you can do is be a good man and treat them with a respect that, at times, you may find hard to find.
I am not a lawyer, but I believe leaving a note like you wrote would look very bad(abandonment/not making an effort-in the courts view), and unless any abuse has been recorded it likely won't have very much bearing.
It sounds like a very tough path, and you have my heartfelt wishes that you will find your way through it. (writing rarely can convey true emotion, and this is definitely one of those times.)
Godspeed.