I Need Your Help

I have always had somewhat of a contentious relationship with Second Eldest BIL. When he first showed up on the scene 20+ years ago, I didn’t like him because he was cutting into my time with Eldest Sister, we were very close, us two sisters. As time went on I found his humor to be relentless and often cruel, and as a young girl who was still coming into her own, I didn’t have the verbal skills to defend myself. I also felt that he, being an adult, should know when to quit(Eldest Sister is 11 yrs older than me and he’s, I believe, another 4 yrs older than her). Needless to say, I had to broach the subject with Eldest Sister, asking her to please intervene on my behalf. She did, and things improved, for years. As I got older, though, things began to revert back to what they were. I would defend myself as best I could, but he was often belittling and down right mean. I was at loss as to what to do, what to say that would finally put him in his place. Often his cruelty leaves me speechless with rage. He reprimands me as if I was a child instead of an adult. “Oh my GOSH DH.” “What the HECK, DH.” Most recently he has taken to calling me gullible. A trait that I think at one time he enjoyed, especially when he could exploit it. Now however, I think he finds it almost disgusting. When I relate a story that I read on the net he calls me gullible. When I relate something I hear on the radio, he rolls his eyes and tells me that it can’t be true. It really hurts my feelings because honestly, I’m not gullible. I feel I’m well informed and well educated. Things that we all pass along via e-mail because they are humorous, he criticizes, in a “Reply to All” scathing e-mail. My opinions are all but dismissed as ill-informed and uneducated. I feel he is mere moments from declaring me stupid. This is exactly how he makes me feel. I’m quite tired of it. I have relayed my anger and frustration to F. But neither of us knows how to confront him. I can’t hold my temper, which means my sword like tongue (my mother’s words, not mine) fails me and is as sharp as a wet noodle. It happened again this weekend. “Guuuullible.” Was his sing-songy comment regarding my presenting Second Eldest Sister with a St Joseph statue, which is suppose to help you sell your house. I looked at F and he shook his head. I don’t know if anyone else caught the look on my face of pure hatred, but it was there.
So anyone, please, how do I deal with this? Short of calling him a fucking ass, which wouldn’t do well for family relations. I’m at a total loss. I need some advice. Help me please!