The 56-year-old actor - who was married to Angelina from 2000 to 2003 - says he and the Oscar-winning actress have always got on well despite their split and they still talk on a regular basis.
Billy - who has been married five times - told talk show host Anderson Cooper: ''Absolutely we're friends. We've always been friends. See in the press ladies and gentleman sometimes if you get a divorce everyone assumes it was nasty and it's not always. It's not that I haven't had a couple of nasty ones, but this was not one of them.''
Billy, 56, recently spoke of how ''proud'' he was of Angelina and her fiance Brad Pitt raise their six children together.
He said: ''I'm proud of the way she's handled having a family.
''She's great for Brad, Brad's great for her. I support them 100 per cent. Angie is a little girl and a woman and a teenager and a ghost all wrapped up in one.''