You know Miss Missy (btw, your screenname cracks me up for some reason- it sounds like a reprimand)
Sounds like you are a very responsible person and that you have worked very hard to be that person. I suspect your family takes that for granted and you probably hear that "you are just lucky" and they have it 'harder' than you...you know that is far from the truth and it probably frustrates you. I could be wrong, but I live that with a few of my sibs, so that is a guess.
I can tell you I was there for a long time. (I am 1 of 5 kids) And eventually, I got tired of being the only one who really gave a crap what happened. You know why? because I was damned if I did and damned if I didn't. If I showed concern and actually held them accountable for their actions, I was being a busy body. But, it was real easy for everyone to expect Wendy to step up to the plate because I was the 'responsible adult' for some reason. I was the rock of the family, always planning everything so we would be together, always taking care of everything. Then, they saw me as a martyr, because I got sick of being the only one. Maybe I was one...so what did I do?
I just walked away, emotionally. Now, I am the bad kid because I am not as involved in the drama. But, it took too much out of me. Seriously. It caused me stress. Maybe I took that on myself, because of my personality. So, the only answer was for me to back off and allow the family to just be what it was. And I invested myself into MY nuclear family more.
You know, it's hard when it doesn't turn out Norman Rockwell-like. It would be so nice if growing up under the same roof meant sharing common values and lifestyles as adults...not always the case. Probably rarely the case, if truth were known. The best thing for me and my sibling relationships was for me to back off and just try to have fun with them when I saw them and know that they will figure it all out on their own and be there if they really need me and I can help. And you know what, if they don't? That isn't my responsibility. And I would rather they think I am the bad kid in the family than keep stressing over their drama. You have to do what is healthy for you, bottom line.
Sometimes there is such a freedom in just letting it go.
And the same applies to your son. My DD is 20 and I have some issues with her too. It's hard to see them make mistakes, especially ones that are so obvious. But, you just have to learn to let it go and allow them to fall out of the nest and crash...if that is what they need to do.
You are forgetting one thing...it isn't written in stone with your son yet. The result of your parenting isn't what you are seeing this moment. He is still finding his way. Give it some time. I'll bet in 5 years, you will say "I can't believe that things finally worked out, I was so worried about you" You know why? Because he really isn't the man he will be until he is settled down and starts his life...on his own.
Many times, that responsible person you raised only really surfaces when they find that person they want to share their life with and have a family with. That is when they get serious. I have seen it time and time again. Give it time. And hold him accountable, even if that means telling him to go do it on his own. Even if it scares you to death to do it. Seriously, sometimes that is what needs to happen for them to grow up and take responsibility for themselves.
You are not a bad parent, you are just dealing with the part that sucks. The part where they are almost gone...but not quite yet. It's like purgatory for parents.
Concentrate on your DD, she is still needing you. Put your energy in that and your DH and you. Your son will be fine, your family will be fine. YOU will be fine. Seriously, it WILL all work out in the end. Today is just a blip on the screen.
I am just a pm away, if you ever need to talk more.