Ok, lets get this "former" Marine thing cleared up.
The way I see it, You earned the title "Marine" when you graduated from boot camp, so you will always be a "Marine".
"Infantry Marine", will be a retired "former" active duty Marine but still a "Marine". Those that served honorably, but did not retire, are also still entitled to be known as a "Marine", but are "former members of the United Statesicon Marine Corps.
The one thing none of us are is an "EX-Marine", no such animal.
Congratulations and good luck in retirement.

Semper Fi,
Joe