Are you serious? IF you are sure of what he's doing, Turn him in.
If you are correct, he is dangerous to people (tried to kill pregnant wife, threatened to kill you and your family). What about the next wife, girlfriend or family member that he thinks is getting in his way?????
If you are correct:
Way beyond the fact that this guy is a fraud and a liar, hurting (no doubt) many more people than you know of, one person like this can and usually does ruin *many* lives. If you are correct in what you say, the problem is way bigger than fraudulent paperwork.
Also if you are correct, he is taking a lot of time to practice and doing a lot of work to perpetrate his crimes, so it isn't as if he is going to stop and think about things and decide to change. He's already made his decisions about it.
You can also forget having him "face up" to what he is doing, or accept responsibility for what he has done and caused. People like that are constantly pointing blame at others and deflecting responsibility for their actions away from themselves- In their deluded minds it's always somebody else who is doing something wrong, and they are often very vocal about that.
So if you are sure you're correct, go ahead and turn him in, then you can quit feeling like his enabling accomplice. He might actually get some help if you turn him in (If 'help' can help somebody who does these things).
Don't tell anyone else you have done so, if you do not want to share it, or if you feel that the fam will blame you for "his downfall".
You are not the criminal here. **If** you are sure you are right about what you say this guy is doing, then turn the evidence over to people who can check him out and verify what he is doing and connect all the dots. Then let them go on and do what they do.
If you don't know who to turn it over to, call the Bureau of Veterans Affairs and ask them.
Everything you have described this person doing is trackable, and there will be a paper trail to support the dispensing of grant money, the fraudulent signatures and presence or lack of official documents, etc. Those documents are in somebody's official file somewhere. He actually may not be fooling anybody, there may be more to it than you know. Remember that, there may be more to it than you know.
Just be sure that you are right before you act, for it would be a shame if what you are thinking were not correct. If he has bragged to you about it then you know without a doubt.
Quit flagellating yourself as if you were committing the crime.