Hello elflauta: Well... to respond to your question, I don't see anything wrong or unhealthy with sleeping with your mother's robe next to your pillow. From what you wrote, it sounds as though you were very close to her.
You mentioned you're 57. And so, perhaps, you'll remain alone at this point. Should you happen to meet someone at some point, & develop a romantic relationship, you may need to put the robe away. However unless or until something such as that would occur, I would say just keep doing what you're doing.
I see this is your first post here on PC. So... welcome to PsychCentral!

I hope you find the time you spend here to be of benefit.
I don't know, of course, if you're here simply seeking advice with regard to this particular concern or if you plan to hang in here with us.

However, should you be planning to continue on (we hope you do)... may I suggest you introduce yourself over on PC's New Member Introductions forum? Here's a link:
https://forums.psychcentral.com/new-...introductions/
There's a lot of support that can be available here on PC. The more you post, & reply to other members' posts, the more a part of the community you will become.

Plus there are the chat rooms where you'll be able to interact with other PC members in real time (once your first 5 posts have been reviewed & approved.) So please keep posting!