i'd take it one-step-at-a-time. rushing into things usually doesn't work well. if you haven't seen him in a long time i think it would be good to spend some time getting to know each other again and see if there is the possibility of something real there. i don't see being vulnerable as an all-or-nothing thing but something that increases over time as one's trust in a person grows. he obviously has a lot on his plate caring for his mom so he may or may not be in a place to get into something serious if that is what you are looking for.