Ste,
You raise a lot of important questions here. First, yes, I do want to know "this fucked up guy" better. I care that he dissociates, but only because I see that bothers him - I know that's a defensive mechanism fromm childhood and I understand it. I have done it myself. The fact that he dissociates means he's taking care of himself with the tools he has at the moment. That's fine by me.
And you CAN recover from the things that trouble you, Ste. You aren't doomed to this. As for dissociation in particular, I guess that's one of those things that you will deal with as you deal with the issues that CAUSE you to diss out. But still, there are things you can do to fight back before that. For example, have you tried to identify situations or memories that trigger you and lead you to dissociate? If there are bad situations that set you off, then it will help to avoid those as much as possible. Or it's a matter of a bad memory, try to link that memory something more positive, so you bridge across from the one to the other. And so on.
I think a lot of us could join you in recalling times as kids when we wished it would all just end. Little Ste thought of this because things seemed so hopeless. Big Ste can help him by leading him to recall the good times as well as the bad and by showing him there is a way forward. All of our lives have meaning and value.
It sure does suck when something happens to embarrass us in front of a new friend, but doesn't that happen a lot to other people anyway? Embarrassment of one degree or another hits us all sooner or later - and not just once!

Sure, to diss out in front of a new friend would be embarrassing, but again, don't take responsibility as if it's something for which you deserve blame. You don't!
I think this is one of those areas where what we mainly have to fight is that problem of fear. If we give in to it we are actually feeding it. Try to see this for what it is; it's just a childhood defense mechanism - you don't need it any longer, but Little Ste hasn't got the idea yet. But by facing it, as you are doing here, that's a first step to rejecting it seeing that there's nothing to be afraid of any longer.
Much love,
Larry