Hi SeBa,
Welcome to our forum.
Sorry to hear you are running into some difficulties right now. I don't know if this is a new poly situation for you, but some poly relationships are rocky in the beginning. Luckily, you can get feedback on this site and learn a lot from existing threads.
It sounds like you are in a V configuration (where you are the hinge). I'm part of a V myself, and we did have some rough years in the beginning. It got easier. It is much easier now.
I hope we can help with any questions or concerns you have.
Sincerely,
Kevin T.