I am an avid student of NT Greek, and your interpretation is one of several valid ones. The problem of course is which interpretation was the one intended? The context indicates a definite possibility that a real apostasy is meant, for the man of lawlessness to be revealed. But departure is an equally valid rendering that the rapture (departure) must occur first, then the lawless one is revealed. Greek is a very context sensitive language, and before you decide on a final exegesis, let me recommend : First, look at the sentences (in Greek) immediately preceding and succeeding this verse. What is their textual context? Secondly, parse the sentences (you have parsed all of the words, haven't you?) as to their tense, mood, and aspect. This is where Greek exegesis gets complicated. The verse is either discussing an event (rapture) or a state (apostasy). What is the tone or theme of the entire book? First Thessalonians is clearly talking about events accompanying the second advent of christ. This is one of the most difficult verses in the book, so first you need to understand the whole book and its message. I have great respect for anyone who delves into the textual meaning of scripture, and you may find little sympathy on this website, but there are resources on the web to discuss your conclusions. I hesitate saying that your conclusion is "right" or "wrong." We are only fallen humans, after all. What I want to say is, do you feel strongly that your interpretation is correct, and can you justify it? This is the heart of biblical criticism. Peace.