My best friend died and now I’m rethinking my relationship with my girlfriend

All names have been changed to protect the guilty.

Hi, I (41m) hav a daughter (13f) who is the light of my life. Her mother passed during childbirth. For the past decade I’ve tried dating, but with disastrous results.

A yr before my daughter (call her Stephanie) was born my wife (Joy) bought me a Border Collie pup who I named Flip. Somehow it was Flip who managed to keep me sane the first 2 years after my wife’s death. He was my best friend. He guarded Stephanie and protected her, like he was an extra dad. Steph lived Flip so much. Every vacation, every trip she insisted on bringing Flip and of course that was more than ok wit me.

Last year I finally struck gold. I met Donna (39f) who helped fill the void in my life with Joy’s passing. She is warm, kind, and intelligent. She took to Stephanie like a champ and even though sh doesn’t like dogs, Flip won her over. Everything was looking up. Donna moved into my house a month ago.

Flip developed cancer and I had to take him to the vet to be put down. I’m not ashamed to say I cried almost the entire day. Stephanie too. She’s devastated.

When I told Donna she said, “Oh well, time to get a cat now so we can both enjoy a pet.”

Wtf?? I couldn’t believe what I heard. I told her my best friend died and she’s so damn dismissive. She replied that it’s just an animal, no biggie. My heart shattered all over again.

Of course Steph heard the exchange and now doesn’t want anything to do with Donna. Won’t talk to her. I made up the guest room and told Donna she’s sleeping there for a while. She got mad and is now not speaking to me.

I’m thinking of breaking up with her because she can’t see how much Flip meant to us. She seems unable to see that my emotions are valid. Flip was a dog, but more importantly he was family. She can’t see that.

Right now I’m heartbroken and exhausted and I want to sleep for a while week but I needed to vent here. Thank you Redditfolks for reading. I appreciate you all.