Hi John...
I disagree with the other poster advising you that not having a job raises a red flag. That's a generalist and blanket statement that really just perpetuates a stereotype. There are plenty of people who don't work (and many really want to work but unable to due to their own disability. there's also unemployment / economic issues) who are very mature, intelligent, and who would make excellent partners. Having a job does not equate to relationship readiness and emotional maturity. However...
Your ex boyfriend does not sound emotionally mature, responsible or maturely able to care? (he slept around and gave you an std, that's serious), or ready for a mature relationship. Like you said, he's an immature dependent. Thank you for explaining the situation with the other "friend" to me. If your gut tells you something, listen to it, especially since you're the one who knows him. Not us. I'm not really sure I have advice on how to ask him about his "friend." I am very pro "no contact" during breakups. It sounds like you're not at that point yet though. I suppose you could just ask him point blank if it's something that's really important to you. Are you still in contact with him? If so, how? Through Facebook?
Also I'm just wondering if you'd said you'd still be a reference for him even though he is your ex now. Thats what it sounded like, and this really sounds like this breakup is hurting you, at the same time.
I want to validate the fact that you said this: "I want somebody to know what I saw in my Ex and why I miss him." First of all, I have heard this from friends before during their break ups, and honestly, it makes a lot of sense to me. I think that if people hadn't been so hurried to tell me to "just get over" my ex, who I loved but hurt me deeply (people told me he was a jerk / loser not worth my thought and energy), maybe I'd have grieved differently. It sounds like your ex had a soft side, was deeply sensitive, caring, and talented. You both liked the same things. You thought he may have been your
soulmate. You thought you could - and wanted to - save and help him. That is very sweet, noble, caring, and compassionate of you.

It's also really ambitious, given the information you've given here! I personally come from the belief and school of thought that we as people have many "soulmates." It's definitely not a one and done deal.
At the same time? I really think that you have dodged a bullet.

Wherever you are in your grieving process today, I wish you wellness and strength. You've been so compassionate with this guy...it's time you're compassionate with yourself now. Take care of
you.