It was required that I leave the logbook with him... he made each entry as we trained and filed my book with the schools other students in between flights.
Are you saying that you were "required" to
share a logbook with other students? By "filed" I assume you meant "filled"? The CFI was logging training flights for more than one student in one book? I've never heard of such a thing. Can't imagine how it would benefit anyone, either... that's a very confusing way to go about it.
There's a reason why there is a space on the first page for you to fill in your name and information... it's supposed to be
your logbook. It's also quite possible that such a practice is in violation of FAA regs. If I were a
Fed examining such a logbook, I'd be sorely tempted to render the entire thing illegitimate... it's just not "kosher".
I don't know who
paid for this logbook, who's property it actually is, but if it contains any information regarding
your flight training, you are entitled to that information, IMHO. You don't need a reason, whether your old instructor will approve of that reason or not. There shouldn't be anything "nasty" about asking for that information, with of course, the instructor's legitimate signature for each entry and endorsement.
FWIW, this reminds me of when my old flight school told me the records of my first solo were "lost" and I had to do it again. with, of course, some review flights prior to that. I had a logbook, it was in there, etc... but the instructor in question had moved on and nobody else at the school acknowledged my argument, and I didn't want to "get confrontational" or change schools, so I let it slide. It cost me in the long run, in more ways than one.
Now, having learned that lesson, were anyone to try something like that again (or what you've described), I'd get nasty, all right. Very nasty. There would be confrontin', for sure.
Never assume that everyone in the flying trades is honest, decent, as knowledgeable as their ratings imply, or even very bright. Trust if you want, but verify, verify, verify. I am very careful now about "oh, that's the way it is" or "it's OK", or "just fill it in", etc.
I am also the quiet, retiring type, but mess with my logbook or the info contained therein, or try to con me, for your own benefit, about what any of it means, and I'll hoist the Jolly Roger. The time, money and passion put into that little book means too much to me.
I cannot fathom how any pilot would "share" a logbook or shrug at the loss of all those hard-earned training entries!!! If you are at all proud of your flying, you need to rectify this.