Very Hard Decision

We've decided that we can no longer keep Mocha. She got under the fence yesterday and attacked a dog walking by. When it's at the point that we can't even let her out in our own backyard, it's time to give up the fight for her. I'm a wreck. I love that dog. She loves us, and I worry about what will happen to her. The place we adopted her from says they will take back any dog for any reason.