If her kids are still living with her, which i'm sure at least one of 'em is, i'd kinda feel funny talking to him. What if she's not around and i have to leave a message with the son? I can't say, it's "so and so", i met your mom a long time ago at "such and such" place. All i could do is leave my name, but if i do that, what are the chances of her remembering me?? It's likely she might not. I'm in a jam, this sucks.
Call up and say you were in a coma for a year and 8 months and now you have amnesia. This way if the kid answers you don't have to explain too much just say you're out of the hospital and found this # in your pocket. She'll probably be intrigued enough to call back.
If she answers tell her the same story but say you are not sure who she is and would like to meet.
Show up with gauze wrapped around your head and act confused. Don't admit whether it's true or not and when she laughs at you for trying something so lame laugh like you don't really understand what is going on but want to fit in.
Ask her to descibe your last encounter in great detail and ask lots of questions about the sex. Tell her your rehabilitation trainer says you are amazing at sex now and would like an objective opinion about your progress since before your "accident" (bring a condom this time)
During orgasm pretend to get your memory back. Start shouting "I remember! I remember!"
Thank her for a very therapeutic time. Schedule an appointment for the next week.