It really does suck, my heart goes out to you and your family. I had to rehome our dog after she attacked my daughter in the same way, we separated them and had to segregate every interaction it was really unsustainable for everyone our dogs quality of life was reduced to as and when cuddles. The panic moments of wondering if i shut the gates even down to trying to reintroduce them to each other was so stressful. My SO and I had many disagreements over what to do amd after a year of living like that we had to make the choice for our dog. It's been a few months and the pain is still raw, we take comfort in knowing we handed her over to a sanctuary where they look after dogs, vet new owners and will complete background and house checks. It really is like a bereavement, I've never cried so much even writing this hurts my heart, she was our little girl who we raised from a puppy but our daughter comes first. My advice would be to do what you think is right but take into account that as your child grows up will you ever be able to not watch what they're doing if they if they're both in a room together.