I mean his in an encouraging way: You probably have not tried everything long enough and in a good enough overall system for it to really work.
You can stop any child from hitting you or destroying things if you are absolutely FIRM enough while being consistent in a loving home. Her whole world should stop and her discipline should be NO JOKE when she attempts that. Every single time, for as long as it takes. You should not be angry, disrespectful (yelling, screaming) or inconsistent. You need to be a solid, calm, rational wall of immovable boundaries. And loving at all other times.
I recommend the book Back to Basics Discipline by Janet Campbell Matson to bypass all the mild positive parenting that will NOT help a child who is this violent. Do that while you seek help, and hopefully it will improve.
If you feel she is medically not able to comprehend things, you should look for specialists, but at 5, if you don't suspect problems with her mind, she needs discipline. From YOU, her mother who loves her, not from strangers. Even if she shipped off to a boarding school (if they have those anymore) who was super tough, her behavior would relapse when she got back home if you do not know how to handle her firmly. You can do it. Don't give up on your daughter now. She needs you for a long life to become a good person.