Why are you confused? You have obviously taken what I said out of context.
If I had said He wishes she didn't exist
you would have a point-but that's not what I said is it?
"I bet he wishes he could forget that she exists" = I bet he wishes he could put her out of his mind and forget all about her.
I hope I have explained myself a little better for you now
I'm afraid you haven't at all. Despite your proliferation of bolded words which you seem to insist upon in every post; your attempt at semantic wrangling does not work for me at all.
Wishing he could forget that she exists would be wishing to forget that the Mother of his children exists, which would lead one to suggest that therefore the children would also not exist - as they were created in her womb.
Have a nice day