Welcome to the site Mike. Glad you found us. You may have already examined a lot of the posts - I'd suggest not too many at one sitting - and found elements of your own experience among them.
fwiw, same age here and also abused about the same age (15-16) by my high school guidance counselor. At that age I had no clue why I just couldn't get it together...and that continued right into adulthood.
In short, a lot of times when you share elements of your story you'll hear a round of responses along of the lines of, "I get it."