I have been separated for 7 years, having been married for 23. For the last 8 years of our marriage, my ex-husband suffered from Clinical Depression. As far as I know, he still does. We have no direct contact.
During the early part of our separation, my ex accused me of alienating our two sons from him. The accusation came to me through my lawyer. While he has stopped accusing me (at least I haven't heard anything more) it was extremely hurtful at the time and I still remember the feeling it caused.
I consider myself a good Mom and I think my sons agree. I'd be lying if I said that I have never said a bad word about my ex to them. After all, I'm human. However, it is his behaviour that has alienated our older son, not anything I said. Without going into it all, my ex is guilty of physical abuse (just once, that's all it took), emotional abuse (saying that our sons would be better off in foster care than with me - if I'm so bad, why didn't he take them?) and financial abuse (he refuses to pay child support), For the first couple of years, I insisted that both sons see their father. Eventually, our older son got to the age where he could make his own choice. He chose to cut off all contact. Our younger son still has a relationship with his father, which I do not discourage in any way.
My point is that just because a child cuts off contact with the non-custodial parent, it's not always the fault of the costodial parent. Some of these people have to take ownership for their own behaviour and accept the fact that they just might be at fault.
Karen