Thank you everyone, Bonesie I hope that guy drops out of your life soon! He seems to be a real a**e. Sorry half of that post was in bold, I only meant to do the one sentence and obviously didn't switch it off again.
I've started re-reading Susan Peabody's Addicted to Love. I read it before (I think someone on here recommended it) and it definitely applied to my male/female relationships. There was a little quiz at the end to see how ready you were for a relationship and when I took it it basically said don't even think about it! That was a while ago now, I took the test again and things have improved

I think I apply those things to all of my relationships, though. I can see that my fear of abandonment is strong (she talks about projecting it on to others, so when someone doesn't respond to your call it blows up into this huge thing instead of being kept in perspective - that's me to a T). She talks about fantasising in order to escape from reality - I do that a lot, more than is healthy (she talks about constructive steps to change reality instead of thinking about it) and she also mentions the matryr complex, which I think I do have with my son.
It's difficult with him. On the one hand he genuinely does need someone with him 24 hours a day. He does need a lot of down time (ie at home, quiet activities, not out and about having fun). He does have a lot of trouble sleeping and all sorts of problems with food, noise, lighting, other people etc. He is very sensitive and gets upset/worried about things (the cat, in particular). So he does have a lot of genuine needs. I have cut a lot of people out of his life because I felt they were abusive and not good people to be around. I've been thinking about whether I've over done that and will keep thinking, but at the minute I'm thinking those people needed to be told they needed to modify their behaviour and shown the door when they didn't. Equally none of them have ever tried to see him since which makes me think I did the right thing but I will keep mulling it over, perhaps I have been too harsh.
It does mean I have left him with no-one who spends any time with him. I have felt very disappointed in friends who don't do anything with him, and my sister who no longer seems to bother with him. I think I need to think about my role in this. What I find difficult is that the people who are happy to look after him from time to time are people that I don't particularly want to be friends with. So I feel it is wrong of me to take advantage of them in this way. It feels quite a selfish thing to do. Will keep thinking on this one.
A lot of my friends from 'the old days' drink, smoke and take drugs. It's not something I mind in other people but it's also not something I want as part of my life. I find this one tricky.
I've been in contact with a couple of mums I know through an activity my son goes to. They are nice people, have children with similar problems, live reasonably nearby. So here's my stupid question of the day:
How do you make friends? Is it just a question of hanging out, chatting and seeing how that pans out? I've realised I've always had a 'special' best friend. Eventually this turns to nothing and then I get a new one. Peabody mentions all or nothing thinking - I think I have done this a lot. So if you just want to be 'normal', do you just spend time together, see what happens and accept it as it is? Sorry, I know that sounds ridiculous, I am approaching friendships from what I hope is a healthier place but I've realised I've never done it before and I don't know how to do it without all the drama and all the bells and whistles?!