I'm so sorry to read that Rosie lost her fight.
Having been through the same with Morgan a little over 3 months ago, all I can say is that you don't want them to go, but you don't want them hurt either.
Your Rosie passed in your dad's arms, and our Morgan passed in my dad's arms too.
Time is a great healer, and whilst you'll think about her last days, they'll soon turn to the times that she was well and she was happy. It's those times that you'll remember and smile about
We have a Dylan too, but we're sure that they know when their 'partner' is poorly. And he will grieve for Rosie too.
I'll light a candle this evening for Rosie's passing. She'll have plenty of new friends to play with at the end of the bridge
Hugs to you and your family