How about an email...


Giving him a heads up that you will be in the area, and that you don't want to catch him off guard and create weird vibes?


You can obviously add the sincere pleasantries (hope life has been treating you well) coupled with a heartfelt apology, and for good measure also assure him that your intention is not to overstep boundaries with your visit or email... A short sincere heads up.


But that's up to you.


Idk, its what I would do in your shoes anyway.