can NOBODY take responsibility in my house????

So tell me if I am being unreasonable.  A little background:  both of my sons and my DH are ADHD.  Right now only the 17 YO son is medicated.  He is a 6'4" tall senior in high school, worked full time all summer and now works part time in addition to school.  He has a girlfriend who I ADORE and she is over by us often, which is fine with me.  She is a doll and very easy to be around/have around.  The 17 YO was also in rehab in February and has been clean and sober for several months now.  By and large, he is a good boy.  It is my opinion that DH babies him WAY too much.  They have this odd up and down relationship--either the 17 YO is all about his dad and I am shit or he thinks his dad is ridiculous and I am the only one who knows anything.  The 17 YO does not know the extent of the financial trouble DH has gotten us into or the three other women that have been in his life in the past 5 years.  So it's kinda hard for me to hear what a hero/great guy dad is when I know what really goes on.  Now here is my issue: over the weekend, the girlfriend was over, we were all home, all was well.  DS was messing around and pulled one of my earrings out of my ear.  The post bent.  It's an expensive pair from Tiffany.  I took it to be fixed and it will cost $60 to fix.  I think DS should pay for it.  When I mentioned it to DH he did not think so because "he didn't mean to".  Of course he didn't mean to, but he was running around giving everyone wet willies and I had asked him many times to knock it off, as had his girlfriend.  He is like a big Labrador puppy--he means no harm, but he knocks stuff over and stuff breaks.  I really feel strongly that DH should pay for it.  So DH backed off.  When I told DS it would cost $60 to fix the earrings he broke, he said "good thing you have a full time job".  So right there he is out of line.  And DH sat there and said nothing.  No "don't speak to your mom that way", nothing.  And I said well, my name is on your account, so one way or the other you will cover that expense.  DS lost his mind.  And DH continues to say nothing.  So DS goes into the kitchen and I say to DH, "you know, to hear from you that a stand-up guy would apologize and OFFER to pay for the earrings would be great, that him paying for them really is the right thing to do".  So DH YELLS into the kitchen "YOU WILL PAY FOR MOMS EARRINGS PERIOD.  DONE." And looks at me and says there--problem solved.  I am so angry I am shaking.  Really? That's what I get?  Why can't he insist that DS take responsibility for this?  If DS rear-ended someone, he really could not say he "didn't mean to" and get out of paying.  What is it with ADHD and not taking responsibility?  This type of thing has happened many times before.  DH gives DS money for stuff he wants that he is unwilling to spend his own money on.  When I insist DS pay it back, he get mad at me because "dad doesn't care, why do you?"  Because it's weasely behavior, that's why.  Because a responsible, mature, stand up guy really doesn't WANT someone else to keep covering them, they want to stand on their own two feet and have some self respect.

thoughts?  DH slept on the couch last night--that's how mad I am.  I am at work all day, so who knows what will go on when I get home.  I am just so sick of being the bad guy.