Separated bonded cats

Hello, I need to preface by stating this decision was something I was incredibly against and was out of my control.

I have an 8 yr old cat that was just separated from his best friend after living together for 7 years. I tried hard to get my roommate to consider leaving her cat with me because the two are bonded (my cat raised her cat starting when she was only a few months old) and I was the one that cared for her cat the whole 7 years but she refused.

They have now been separated for about 3 weeks and my cat is starting to show signs of greif by sleeping all day, sleeping in weird places, crying continuously and searching the house. My partner and I have been trying to do our best to keep him entertained with new toys, walks, pillow forts etc. He has just been getting worse. I even got him on prozac a few months ago to prepare for this.

My question is would it be a bad idea to let the cats visit one another in a neutral environment? My former roommate lives walking distance away and we pass her apartment when I take him on walks. I just can’t decide if it will be beneficial to both of them or if it’s going to set him even further behind.

Feel free to ask for any other info!