Divorce Support Forums: need advice on boyfriends situation

hey guys I'm new here and needed some insight on some things. my boyfriend and I have been best friends for a year now and just started dating about 2 months ago. he had left his crazy wife (i knew her too so I can honestly say that.) about 3 months before we met. well over a year later there has been 3 papers drawn up and she even signed one set and then started accusing him of changing them. they have 2 precious kids together that I love very very much. I give them riding lessons at my stable.
she has been very childish through this whole divorce. she has moved in with guys, done drugs, left her kids at her moms on her week to have them to go to the club, heck she even left them for 3 months and didn't call. now that's not even the worst part. he was livin with a friend of his and she went as far as breaking in (more than a few times actually). now when you talk to her all she can talk about is him. if you ask her about her kids the only thing she will say is 'i love my kids' and continue talkin about him. she rides by his house multiple times a night. will call him 30 times in an hour. she sends him texts all night long. when she has the kids all she can do is stay on the phone constantly. she doesn't like the fact that the kids would rather be with me and him. we just got them brand new bunk beds and games and a big screen tv. they love to come to my house and ride horses and tell me they love me all the time. she has gone so far out of jealousy to say she is going to have it put in the papers that I can't be around them. how ridiculous is that? can she do this?

now he doesn't talk about her at all. all he is concerned about is his kids. he has been mature about the whole thing.
now here is where
I have a question... he told her he was takin the kids to one of my horse shows with me for the night and bring them back the next day (today). she had a fit and told him she was going to have him arrested. this is his week why can't he take them 2 hours away for the night? she has stressed those kids out so bad that they need to get away. they deserve it.

he is going for full custody. she has no job, her parents kicked her out, she is living with HIS ex girlfriend (this is the 3rd one she has moved in with btw), she is constantly pawning her kids off on people so she can go 'out' and has no place for the kids to sleep.

can you give me some kind of insight on what kind of actions he should take? he is actually a really good guy. he coaches both kids ball teams and is there for everything. I think he missed a grillout because he had to work. she is constantly degrading him in front of the kids and everyone else. I just don't know what to say to him to help. she constantly blows my phones up. I have gone so far as to tell her if she called me again I would have a restraining order put on her and harassment charges filed.

any advice would be helpful. I just don't want to abandon my best friend and leave when the goin gets tough ya know? afterall he has been there for me through a lot of stuff so I think I should stick around and kind of be his rock since he has been mine for so long.