Solution to turtles being aggressive toward each other: Separate. If they don't want to live together, don't force them too. It's like when two college roommates are forced to stay together and they both hate each other, like a jock with a nerd.
As far as your turtle being aggressive toward you, comes with the territory, my friend. One of my smaller turtles, Typhoon, started a biting habit with me. So, whenever I held her, if she opened her mouth to bite, I would place my finger under her lower jaw and gently push her mouth closed, then give her a chin rub. It's like I had to assert who the boss is, and then condition her to accept that being held by me was not threatening. Kind of like how when disciplining a child, you follow no, with yes. No, you cannot bite me, but you can have a chin rub! LOL XD
