Complex sentence: Because of his Alzheimer's disease, Junior barely recognizes Tony and becomes confused when Tony tries to remind him of his involvement in "this thing of ours," whereupon Tony abruptly leaves with a tear in his eye.
Split into simpler sentences: Because of his Alzheimer's disease, Junior barely recognizes Tony and becomes confused when Tony tries to remind him of his involvement in "this thing of ours". When it becomes obvious to Tony that Junior has little to no memory of their history, he abruptly leaves with a tear in his eye.