I am so sorry for your situation and for the mess this board is right now.
From the heartbreaking story that you have told, I really don't think representing yourself is a good idea. Because of all the emotion that you have (and should have) it will be difficult for you to play the role as a logical lawyer. Now, I don't know you personally, so I may be wrong, but I understand the pain you are in and in my own heart know that it would be difficult to remain calm cool and collected as a lawyer would.
Anyway, you need to read up on PAS and HAP. Parental Alienation Syndrome and Hostile Aggressive Parenting. It sounds like you have been steeped in this for years. This may be a good way to try to understand what you are going though and what other people have done to mitigate the situation.
In my own experience, there are tricks you can do to help your relationship with the kids, but it is next to impossible to have a "normal" relationship with them if a controlling CP doesn't want it.
Do you have joint
legal custody or does she have sole? If you have joint legal, there a plenty more options to you.
Have you tried writing letters, email, calling them often? How about setting up a webpage, like myspace or facebook, that has all family info on it for them, pictures of your times together and other things you have been up to. You can use this page as a place to "write" them letters they can view whenever.
First of all, being uncomfortable around you should be no basis to keep the kids from you. As a matter of fact, they should see you more so that they could get a more comfortable relationship with you. That is the world of "shoulds" though, not real life. Your ex sounds like she wants any excuse to be the kids only real parent.
Keep posting on this page. Besides the occational childish bickering that goes on (the reason why your post got bumped down...), there are many very helpful people here that are dedicated to helping out people just like you.
Best wishes,
Ref