Girlfriend with needy best guy friend

I've been dating this lil hawtie for a few months now (Ive known her since January though). I put a thumb in her butt the other night during sex so we're at that level of our friendship. She has this guy best friend that she has known since highschool. He calls her constantly, literally everytime Im hanging out with her she gets a call from him. I finally said something to her about it recently, a very casual "yo wtf is up with this dude." She goes on to tell me that all her past bf's have had problems with this guy. This dude even gets pissed at my chicks female friends if they are taking up too much of her time. Come to find out he has a past full of family issues, crazy siblings, parents are divorced, etc...

At the end of the day though, this guy is 28 fucking years old. I have never known someone (much less a MALE) to be so needy about a "best friend". My girl acknowledges his behavior but doesnt set any boundaries (a psychologist once told her shes an "enabler" type for her friends). Even if I told her to set some boundaries with this guy I know she would have problems doing that... I havent met him yet but I know I will in the near future. Dude already feels negatively towards me cause I spend time with my girl. I was wondering if any of yall had advice on how to speak to this dude when I meet him. Initially I plan on befriending him and seeing where it goes from there.