GW.....I am not a professional but I can talk to you from my experience with my W. She has been on depression meds ever since I have known her and her mother is a hot mess. She is on about everything a Dr could prescribe. IMO, yes professional is help is needed probably from an IC and probably a lot more.
The thing is I feel the same way about my W...not saying she was unhappy with me but from what I have contributed to our downfall I will own about 10 to 15%. That said I can't force my W to get any help and only she can recognize she needs it.
It is something I can't control so truthfully I don't worry about. Either something happens and she is realizes it or she doesn't. My W often in our relationship indicated she felt flat emtionally. Not necessarily dead inside but it was probably something similiar.
I am sorry you are in this situation. It is truely a helpless feeling but there is nothing we can do. Again IMO.