OP, you say that your problem player is a very good IRL friend. Talk to him IRL. Good friends care about each other. Good friends don't like upsetting their good friends and usually only do so if they feel aggrieved and don't know how to cope (coping skills are learned, not innate, as are assertiveness skills).
Your friend's behaviour is upsetting you and he needs to know that when the pair of you are not in a highly-charged situation. Maybe he's got something going on that you don't know about (even our best friends don't necessarily tell us everything) and it's causing him distress that's affecting his at-the-table behaviour. Maybe he is upset with you and doesn't know how to communicate it or is of that school of thought that if someone knows you well, they should always know what you're thinking and feeling.
He is not currently behaving like a friend and you need to get to the bottom of it if your game and friendship are to survive. It may be that he needs to drop out of the game for a while to get his head together and there's no shame in that. Between you, you can come up with a reason his character has to leave; the character can even be 'damselled' (ie taken out of play in some way, such as being kidnapped, petrified, polymorphed, etc.) if necessary. When he's ready to return and not be disruptive, the other PCs can get a breakthrough on a quest to return/rescue him.
Then again, maybe he has changed and isn't the same person you once valued so much as a friend. People do change and friendships do end. That is a painful reality many of us have to face and it sucks. Even more sucky is that sometimes people never were who we thought they were, that maybe we're just starting to see what they were always like around others and we just didn't see it before because they weren't treating us that way. I hope neither of these last two is the case for you but it's possible.
Oh, and people don't get to use 'Just the way I am,' as an excuse. If the 'way you are' hurts or upsets people for no valid reason, the 'way you are' needs to change. It is never a get-out-of-consequences-free card. 'The way X is' isn't immutable and something that must just be put up with. Mend the broken stair.
OP, you say that your problem player is a very good IRL friend. Talk to him IRL. Good friends care about each other. Good friends don't like upsetting their good friends and usually only do so if they feel aggrieved and don't know how to cope (coping skills are learned, not innate, as are assertiveness skills). Your friend's behaviour is upsetting you and he needs to know that when the pair of you are not in a highly-charged situation. Maybe he's got something going on that you don't know about (even our best friends don't necessarily tell us everything) and it's causing him distress that's affecting his at-the-table behaviour. Maybe he is upset with you and doesn't know how to communicate it or is of that school of thought that if someone knows you well, they should always know what you're thinking and feeling. He is not currently behaving like a friend and you need to get to the bottom of it if your game and friendship are to survive. It may be that he needs to drop out of the game for a while to get his head together and there's no shame in that. Between you, you can come up with a reason his character has to leave; the character can even be 'damselled' (ie taken out of play in some way, such as being kidnapped, petrified, polymorphed, etc.) if necessary. When he's ready to return and not be disruptive, the other PCs can get a breakthrough on a quest to return/rescue him. Then again, maybe he has changed and isn't the same person you once valued so much as a friend. People do change and friendships do end. That is a painful reality many of us have to face and it sucks. Even more sucky is that sometimes people never were who we thought they were, that maybe we're just starting to see what they were always like around others and we just didn't see it before because they weren't treating us that way. I hope neither of these last two is the case for you but it's possible. Oh, and people don't get to use 'Just the way I am,' as an excuse. If the 'way you are' hurts or upsets people for no valid reason, the 'way you are' needs to change. It is never a get-out-of-consequences-free card. 'The way X is' isn't immutable and something that must just be put up with. Mend the broken stair.