Wow, it must feel awful, not haveing any control over what happens to your own son! I am so sorry for you, I can tell that your heart is broken.
Your anger towards your ex girlfd is certainly understandable, however, I don't think it would be a good idea for you to meet with her, considering all the pent up anger you have right now. If you were to get into a fight with her and her boyfd, it might reflect on whether you will eventually receive visitation rights with your boy, and your boy is more important to you than anything else right?
I know that what has happened is unfair, and I know what it feels like to be helpless and unable to control the outcome as far as your boy is concerned.
I wish I could give you answers and take away your pain. Sometimes, it helps a bit if you write your ex a letter, only DON'T send it to her...put in writing exactly how you feel about her and what she has done, swear if you have to, whatever it is that you are feeling, get your anger out on paper! Also, after you've calmed down some, maybe you could write a letter to your little boy, telling him how you feel about him and that you WANTED him! When he is old enough to read it, believe me, it will make him feel good about who he is because he will know that his daddy loves him!
I'm sorry I could'nt give you more ans...just know that I will be thinking about you and wish you the best