Ok, I took a bath and thought about it and was hit with an idea. I think it only fair that I let him know I found his journal and I offer him the link to mine. Anonymity is important to me, it's actually very important. I grew up in an environment where boundaries were not respected so now I have boundaries and I value them. Something tells me that my nephew, Thomas, understands the need for boundaries and will also respect my boundary.
That is the issue, isn't it? Boundaries. When I stumbled across his journal it became a boundary issue. I like Quid Pro Quo, so maybe it is only fair that I give him mine and let him know I found his and we just both agree to keep each other's presence to ourselves. I will ruminate the matter and then make a decision.