Maybe a different "therapist" (don't know the term in English, mediator? ) isn't a bad idea.

Our current one is married, and have kids. But she said "a new partner can be a good thing, b/c then the child will have yet another person in his life who loves him"

I just disagreed, but didn't go into it. She was good on all other points, but I mean, what?
Who says that to a couple right after a break up?
Yes, a long term partner will most probably give the child love.
But when jumping into a new R straight away, I don't see this as the likely outcome.
I've seen first hand how it can confuse a child when it turns out just being a rebound.

I will follow your advice and make the proper preparations.

Together for 8,5 years.
S2
Interest in OM.
She left 29.09.12 b/c we couldn't work things out.
No signs of OM, not digging.
Living in seperate homes, sharing custody.