Is this an isolated incident? Compare your new, shiny Ring to what the other members of the party have gotten so far. If everyone else has been given items of equal power, if you DON'T use your overpowered-for-a-5th-level-character item, you'll be left behind. How about the enemies he's throwing at you; how are they equipped?
It might be that the over-powered items are being given out intentionally; maybe the DM wants to run a high-powered game. Find out if that's what the DM wants...and if it is, go wild. You might want to let your "inner DM" talk to him about the consequences of such a game, just keep in mind that he might have a plan, after all.
As for the in-character issues of feeling cheated out of a lifelong quest here's what I'd do. It's a level-based item, right? Play up the research-and-discovery aspect of it; the character is always seeking to unlock its' secrets, and greater powers (ie higher level spell slots). Maybe the ultimate goal is to create his own version of the ring, someday. This way you can have your cake and role-play that you're eating it, too...
It might be that the over-powered items are being given out intentionally; maybe the DM wants to run a high-powered game. Find out if that's what the DM wants...and if it is, go wild. You might want to let your "inner DM" talk to him about the consequences of such a game, just keep in mind that he might have a plan, after all.
As for the in-character issues of feeling cheated out of a lifelong quest here's what I'd do. It's a level-based item, right? Play up the research-and-discovery aspect of it; the character is always seeking to unlock its' secrets, and greater powers (ie higher level spell slots). Maybe the ultimate goal is to create his own version of the ring, someday. This way you can have your cake and role-play that you're eating it, too...