Ahh just saw your message - I am happy for you.
You know if there was any chance that you two did get back together its not going to be now is it?
I think you both need to get on with your own lives and have a friendly relationship around your child for his sake.
My friend who has recently had councelling because of many failed relationships said that it all boiled down to her mum and dads relationship. They spilt when she was younger and can you believe she has not one memory of them in the same room together? She said that she suffered because they were too selfish to put their own crap to the side to make happy surroundings for her.
To be honest they probably thought that it was best they saw her separately so they didnt argue but its not. I am not saying you and your ex should have happy holidays together but you should be able to be in the same room and have a friendly (if poss) relationship for your son snd so he feels its nothing to do with him etc...
I guess to get to that point it may take a while at first.
Anyway back to my original point, if you two ever do patch things up it will be when you have both been separated for awhile, he will miss you and regret what happened. If that happens and you are willing to try then you should have coucelling and see if you can forgive him. Its hard to forgive and forget isnt it so I guess you would need help with that.
But for now you need to concentrate on YOU - its all about YOU and your son so enjoy spoiling yourself and make plans for things YOU like and things YOU want to do that you may not of been able to do before.
I think its a good idea to read up on dealing with separating with the father of your child because these things are not always obvious to us especially when you are in the situation.