In answer to PO’s question, there is no easy way to tell your parents about your current situation but nit is probably better to tell them then to have them find out through other means. Be prepared for a deal of turmoil anguish and recriminations. Make every effort to tell your parents that it’s not their failure, that nothing they did forced you away, that your lifestyle is not a reflection on their parenting, that you love and respect them, etc. but remember that they will be terribly hurt by your revelation. If they may, over time, come to terms with your decision.
While they probably will never accept your lifestyle, they may still maintain a loving relationship with you. However, be prepared for the possibility of that they may totally, or almost totally sever relations with you. You seem like a level-headed, mature young man. Certainly your military service has taught you to prepare for the worst and that “no plan outlives contact with the enemy”, I.E. things are certain to develop differently from what you expect, at least in some respects. I wish you good fortune and hope and pray that you will eventually return to your people and your G-d.
P.S. This fellow is an illustration of a point I have been making for years. OTD and “at risk” are not the same thing. “At risk” implies engaging in self destructive behavior. This guy isn’t a druggie, isn’t “hanging out”, Isn’t a threat to himself or others (yeah, except to his neshama). He seems rational, oisgehalten, put together, etc. The fact is some people simply come to the conclusion that Religion just isn’t for them, no risk involved.
PP.S. MDD, you can be as judgmental as you like. Your judgment and and mine are worth bupkes. The only judgement that counts is that of the Dayan HaEmes.