I too can relate. My husband left his wife and 5 children. Just like he left his first wife and two children there to move in with a bipolar woman he met in a psychiatric unit. I also have to wonder what kind of woman wants a man with 2 wifes he has left and 7 children. I have no advice but just to tell you to hang in there.
My children also hate the OW and have only seen her once. My step children whom call me mom and love me unconditionally also say they are coming to me for the holidays not their dad. He is addicted to this needy woman who has the same illness as him and in the meantime has given up his relationship with the children. I know it is very hard but just be there for your children, love them, and let them know they are loved even if bad choices are being made. When they get older they will see the truth and see everyone for who they really are.
I know this because as a child I went through this and now I am going through it as a wife and mother.
Hugs and hang in there.
M 32 H 39 SS 15, SD 12, S11, S9, D7, D6, D4 E/A 02/06 WAS 03/06 RH 05/06 On 07/07 told me he wants to leave again. On 08/11/07 Walked out again.
People say "When God closes a door he opens a window." They forget to tell you "It is hell in the hallway!"