It entirely depends on the people. It can feel like a relief to establish the connection again, but can also feel extremely disappointing. A couple years ago I tried to get back in touch with an old friend who moved away after high school to a different state. It started out great, we both missed each other (she said so anyways) and we talked about recent things. I didn't talk about anything depressing either, but after that first day conversation completely died again and since she's a social butterfly it's a bit odd, so I'm just choosing to leave it alone. She has new friends and a husband now so there's no room for me in her life it seems. If she wants to talk she knows my number now.

Please don't use my personal experience to say "it will definitely be bad for me too". I've seen plenty of cases where it worked out great. I think at the worst you will end up getting some closure from this. It seems you want to reconnect with her, but I'm assuming her lack of knowledge on MI is the problem? Perhaps you can try educating her, and if she isn't receptive then maybe it will be easier to just move on with your life and leave her out of it.