Joining the party a little late here, but anyhow:
Mobby -- Yes, alcoholism and other addictions are frequently found in Ns.
wrt not boasting or mentioning the famous acquaintance -- maybe this is something she is saving up for the right moment? When you've gone to tea with the Queen, she will swamp you with stories of whatever famous person she knows and you will manage to get two or three words in about the corgis and how funny Prince Philip was...
Feelingpositivemum: I also have a DD who refuses to talk to her N father. She cut him off when she was 15 and I have supported her in her decision. My exH tells people about the situation as a way of garnering sympathy, painting me and DD as a pair of vindictive hags, and contrasting himself as the ever loving blah blah blah. Of course, he does not mention what sparked the decision of DDs (horrible physical mistreatment of DD, bullying, raging at her over the years, threatening to destroy homework she had spent hours doing one particular day when the whole mess boiled over). Since he sees no difference between the children and other adults as far as how he treats people, I think he honestly doesn't understand that others will not judge DD as brutally as he wants them to in this situation. Everyone else has expectations of behaviour of teens and of adults that are distinct: adults are expected to be adults, while teens are allowed a little indulgence in most people's minds. ExH's calculations on this score also fall apart because DD was an exceptional student and nice person who never put a foot wrong in school -- his attempts to place any blame on her for the development of the standoff are very see-through to everyone who knows anything about DD1, and those who don't know her don't matter to me or to her.
If you can show a pattern of your ex following you from place to place and moving in too close for comfort, can you get a restraining order of some kind, as this is a form of stalking? I would trust the professionals in the ED unit to make the correct judgement of your ex, but I would also be tempted to tell it like it is to them if you get a chance. The family dynamics involved when one member develops anorexia are complex but also fairly predictable. DD1 didn't develop anorexia, but she was very food-averse for many years, and oppositional when it came to eating, fwiw.
Nordana I feel you need to step back a lot from your DS and let him muddle through. I have the sense that his constant worrying about his appearance is really an inarticulate way of expressing some other insecurity, and really it's the job of his therapists to help him sort himself out, not yours. The trauma he experienced in school has clearly wounded him deeply and shook his self-esteem and confidence, and perhaps affected his relationship with you too, if he couldn't tell you what he was going through at the time. This is the work of therapists though, not you, as he is a grown man now. Have you experienced any counselling yourself to deal with the fact that he didn't confide with you at the time? Do you think your close involvement with him and his problems now is an attempt to compensate for being kept out of the loop when he was younger? Do you feel guilt you mention he may have been suffering at home with the older brother with ADHD?
Maybe he could be encouraged to try volunteering with people who are down on their luck, or mentoring children who are facing obstacles, just in order to get outside of himself for a bit, gain a sense of perspective, feel he is making a positive difference in the lives of people who are in difficulty?
I also think that trying to emphasise the things that he is good at, the good personality etc., when he brings up the problem he has with accepting his appearance can only have the effect of refocusing him on that one aspect of his life. It comes across as overcompensating and has the double negative effect of making the real positives less believable.
I would be inclined to ask him if he thinks he should have any particular kind of physical appearance (does he deserve something perfect?), and what exactly he wants to do about it to change things if he's that unhappy and he thinks change might be possible. There is the facial hair option for men, or even plastic surgery if he thinks that would do the trick.
I also think your comment on Ronan Keating was telling while RK isn't exactly my cup of tea, I do think he's good looking but I would not describe his features as 'sensitive', and I wonder if this is how in fact you see your DS, and if this has become a self-fulfilling prophecy that you have communicated to him that he is sensitive; sensitivity can have real drawbacks in the world of boys and men.
I suppose what I'm saying essentially is to shrug and say 'So what?' when your DS complains about his appearance or sees the glass half empty; a man who has his own business, a steady GF, suave, blond, boyish good looks like Ronan Keating (note, not 'sensitive face', you can reframe things), who comes out of a business meeting thinking people have not warmed to him because of his appearance might need behaviour therapy, just to change his thought patterns and examine his assumptions.
Oh yes, Mobby gifts and tying people to you with material things. money this was and is exMIL's M.O., also exH's... Watch out for the way your SIL treats your DCs. Children are defenseless and very vulnerable to N's in their lives, because of the highs and lows involved. They can really, really wound a child by a remark. Make sure you 'debrief' the children if they ever spend time with this SIL, and deal right there and then with any things she has said or done that have left the children or you (you seem to have excellent N-radar) feeling a bit upset.