Dear Justforkids,
Being a mom myself, it is unimaginable what your children's mother is doing. Unfortunately my husband is going through the same ordeal, except they are teenagers now and are girls. They have been told to choose sides and when the girls have shown love and affection to both their dad, my kids and myself - the wrath is waiting for them when they get home from their weekend. Texts are being sent on a continual basis asking for them to spy on us when they are with us, to look around for documents, and when my husband lost his job earlier this year - she tried to involve my own kids (through her youngest) in an attempt to get information that wasn't there - he was unemployed and not working. I have no respect for these types of women who really give us "normal" and respectable mothers a bad name. I hate nothing more than women such as your ex and my husband's ex who take such joy in hurting their own kids to satisfy their own insecurities.
My suggestion to you, since your kids are still young - at least for the 8 year old, reaffirm as often as you can, document EVERYTHING, get a good lawyer - preferably someone with a reputation of no tolerance for child alienation - usually a female lawyer is more equipped for the emotional battle and has no respect for women who do this to their own children. In this world we complain about dead beat dads, I am seeing great fathers who are being treated unfairly just not by their ex but also by the courts. Something needs to be done to discourage this kind of behaviour - you still have a good chance of saving these kids from such poison - love them, keep in contact with them no matter how hard she tries to stand in your way. You sound just like my husband who feels like his hands have been tied behind his back and there is nothing he can do - i wish more fathers would stand up and prove that child alienation is happening in the country and that whether its the father or the mother - its wrong and needs to have serious consequences. I heard of a woman in Brampton, who lost custody of her children because of such actions. Maybe you might be the next father who could win for the rest of the dads out there.
Good luck and don't give up, no matter how negative or depressing it gets. At least your kids can say that you NEVER walked away, something that even she can't take away.
Take care,