How do you deal with this problem: you have an old friend who wants to re-connect. You really care very much for this person. He has enormously good qualities and is loyal and decent, but he suffers from such ferocious anxiety and other emotional disorders - mainly caused by "family of origin issues" - that it makes him manipulative and in some ways actually kind of dangerous to know. A long time ago, you were pushed to making the drastic measure of cutting off all contact because of it all. It was very painful because for a while you'd been fairly close.
He isn't aware of the motives for most of his more difficult behaviour, and spends a lot of time fairly confused about why he can't keep his friends and relationships better. He suffers a lot because of the awful lies his evil brain tells him all the time.
When he's relaxed and not feeling threatened he is smart, fun, interested in the same kinds of things and a genuinely warm and good soul. On the side of the angels, and all that.
He's also very lonely because of his brain-troubles and has reached out to you on FB.
What would you do?