Thank you for the input. I wanted to reply earlier, but couldn't sit down at the computer until now.
Many/most encourage me first and foremost to protect my rights / kids' rights through legal action, which is something that can definitely be done, I have been in touch with my lawyer already...and yet I hesitate. Pek64 and Ruebelin you ask me what I'm afraid of, and I try to pin point it in my mind. I am not afraid he will take the kids out of the country, he has already stopped seeing them here, on his regular Saturday nights. He has point blank stopped seeing them since he found out I was seeing someone. He only took the kids for an ice-cream one Wednesday afternoon for less than 1 hour, to tell them that they have to be more accepting of his new family and that he may in the future have to work outside of the country (I believe he is easing them into the idea). He already stopped paying child support two months ago, so I'm used to not having any money from him....I guess what's happening is he has copped out of all of his responsibilities, and now he's finding new ways to make me suffer. My fear of him is probably habit/deep-rooted something. His anger makes me feel feelings of fear and guilt. I guess I feel guilty that I didn't tell him I am interested in someone, which is something we had agreed to do, and he claims he told me about GF last year as soon as he felt interested in her (which is not true though, he told me/us in August, but had met her in February and was in touch long distance for all of those months. Then GF arrived here on a Saturday in August, he told us about her on a Monday and on the Wednesday she had moved in - so he's being a bit hypocritical). I felt no need to tell him I was interested in/seeing someone, mainly because of the fact that this man is moving abroad, and will therefore not be a part of my kids' lives, or be a part of mine other than as a friend, EVEN THOUGH for the coming month I will be seeing him romantically (does that make sense?) somehow it does to me, i.e. I'm enjoying a bit of romance, but am fully aware that I has an expiration date on it, and therefore am not 'announcing' it to anyone). Despite all of these rationalisations, I feel guilty for not telling him, I hate not being truthful.
Some moms have mentioned I should write a well-pondered letter in response to him and GF, others say I should just stay quiet, not mention anything..... I'm undecided about this. On one hand I feel I should defend myself and the kids and reply (pointing out how he's being hypocritical, and also that I'm not the source of all of their problems and am not a scapegoat, am not an excuse for their decisions, etc..), on the other hand I don't feel I've done anything wrong (except not tell him about this guy) and don't need to defend myself from their attacks, and silence is probably the best response - except is it just because I'm too chicken? or is silence REALLY the best way to go?
Ugh, the feeling is awful, it's like a heavy weight. What I am unrealistically hoping for is that I REALISE that the court decided our separation agreement, I have rights, I have done nothing wrong, there is no other man living in my house or hanging out with my kids, and therefore I can LET GO OF THIS FEELING OF FEAR, and get on with my daily life as usual.
A couple last things: I also fear that with him going away/not having the kids, that I will no longer have any free time to continue my 'adult' social life which I was really enjoying every Saturday night for the last 18 months :-( That's a real bummer, a really big bummer. But at the saem time I realise this is exactly what he wants to happen- that I don't have time to have a social life.
AND, he has forbidden me from getting in touch with his parents i.e. my kids grandparents, who told me they are always willing to have the kids over if I ever need it, and therefore he has cut off that bridge of hope for me. And in GF's letter to me she told me she told his parents all of the dirty laundry from my past (pre-marriage), so perhaps now they might even have a very poor opinion of me :-(