Do you have any advice for a single mother whose daughter is starting overnights stays at her father's?

I’m a single Mum, my daughter is 3 and we live in Australia. She’s started overnights with her Dad, who lives 3 hours away (his choice), so I have to take her up once a month for her overnights. When she gets back from those she starts telling me that I’m not her friend and only daddy is her friend, and that she wants to go live with Daddy. Her Dad doesn’t pay child support, left me for another woman, and is very rarely there for her. I am not going to share this info with my daughter at all, and I always have encouraged her to have a great time with her Dad. He and I are good face to face, so she has (I hope) no idea that the relationship between her Dad and I is tense. Her Dad also is with the same woman he left me for and she’s awful to me and sends me rude and nasty emails all of which I just ignore. How do I deal with this in the right way in front of my daughter? It’s heart breaking to hear her say these things, and I normally end up leaving the room to have a cry. He has his ‘family’ and I don’t have anyone. I’m finding it a bit tough at the moment so I’m coming here for support. Thank you.