First, let me apologize for the length of this message.  I have been struggling with this situation for so long I guess I needed to vent some also.

My son signed up for the Navy and had to wait 6 months before he could leave for boot camp.  All he has wanted to do in the last 4 years has revolved around the military.  He was so excited and ready to go.  About a month after he enlisted he started dating a girl that was much younger than him, against all of my families wishes and protests.  No one approved, but I had no help in trying to stop the relationship before it got serious.  By the time he left for boot camp the girlfriend had basically pulled him away from all of his family and friends (we are a very small town and close knit group).  To make matters worse, as the relationship progressed we found out startling and disturbing facts about the girl that just made it harder to accept her.  My son as since graduated boot camp and is in his 3rd week of A school.  Ok so here is what has been going on and why I'm asking for advice.

We found out that about 6-8 months before her and my son started dating she was having some pretty serious mental issues.  So much so, that her family had thought of putting her into a behavioral facility for help, but that never happened.  She has lived a pretty rough life.... her parents married young and divorced years ago.  Her mother is pretty much a loser and drug head.  Her dad works for a pipeline and is only home about 3 months out of the year so her and her brother basically live with her dads mom(who of course has raised her children and isn't interested in raising anymore).  So basically the girl just does what she wants.  That being said, when her and my son started dating, she was only 14 and not an innocent in anyway (if you know what I meant).  My son on the other hand was a GOOD child.  I know all mothers think their kids are perfect, but I have a daughter who is a hot mess and a handful, so when I say he was GOOD, I mean it.  When he got his drivers license we got him a truck and said go.  He was always telling us where he was, when he would be home.  Checking in all the time without us every having to ask, we have always been a very close family.  When he started dating her, he started lying to us, sneaking out, not coming home until we made him.  He wrecked his truck and got a speeding ticket.  All in the first 3 months they dated.  So fast forward to PIR... he gets his phone back and I have already synced one of my old phones to his iTunes accounts because she had been leaving disturbing voice mails while he was at basic and I wanted to keep a watch out.  Well in the last 3 weeks, she has threatened suicide 3 times and told him way more than that, that she wanted to cut herself.  I printed out one of her texts and had a meeting with her father and his reply was " well her mother was a cutter".  WHAT?!?!   I was completely shocked.  I thought he would get her some help, but he went home, packed her up and drove her to A school to spend the weekend with my son.

So while my son is trying to get through A school is constantly worried about upsetting her, he is constantly apologizing to her for being late returning her texts, or not being able to call her when she's ready to talk.  I want to scream to her "HE'S IN THE NAVY...... he can't tell his CO "hold on while I text my GF" Now she is pressuring him about getting married and apparently he asked her dads permission a couple of days ago for him to sign parental consent so they can get married.  Again I say  WHAT?!?!?

Yesterday though, was the straw that broke my back, but I find myself at a loss as to what to do.  She was at it again with the "I want/need to cut myself so the pain will go away" and my son was so upset he told her he wanted to cut himself to see how she feels!!! That was it for me, but I don't know where to go from here.  Everyone I've talked to in my family and church family has told me to call the base and talk to someone over his barracks or school and let them know what is going on.  I don't want my son to get in trouble, but I want him to not be so stressed about this girl. Her father apparently doesn't care and just wants to lay the responsibility of raising her on my son. 

I'm so sad, I just don't know what to do anymore.....

Please....ANY advice would be helpful.