This must be a terrible double whammy to cope with. Not only are you probably feeling bewildered by the lies and the betrayal but you are faced with the prospect of your children (are there some more that you had together?) going too. The fact that you accepted her child as your own too, must hurt in that she seems to have given you no respect. First of all, if you have had a good relationship with the child and it sounds as if you have, I would not worry too much about that, as you will always have a relationship and if they are now grown up they will probably not be too happy about it either. I would advise not to let her 'side' with you or appear to, as that will only make things worse. I think the only thing you can do is just be as calm as possible and make sure that you do exercise your rights, in that she cannot take your children out of the country I don't think, although it might do more damage to prevent it. I think the whole thing will go pear shaped in a few months, she has gone mad as you say, and the children may well need the stability of the home again if it does.