You can quit. Almost everyone here has done it at least once. With enough will-power, one can "stay quit". Barring some type of mental illness, most adults can govern their behavior at least that well. My question is, "Why would you want to?" As virtually anyone here can tell you, resisting that which is part of our nature is probably not the best choice if long-term happiness is the goal. For some, such resistance can have profoundly negative consequences - witness the staggering suicide rate among the transsexual population.
The trick is to find balance, that point where you can express that feminine part of yourself and live your life. And yes, finding that balance can be tricky. Where mine is may not be where you find yours. My advice is to find it as soon as possible so that you can enjoy the rest of your life happy and fulfilled. Professional counseling can help, but it requires your commitment to the goal and your willingness to answer difficult questions with ...let's call it "daring" honesty. You can take the long road, as many of us have (myself included), but I would recommend against it. That road is often littered with unhappiness, failed relationships, or worse.
One last thing. Don't purge. When you finally reach the point where you realize that it's too painful to continue to deny, having purged will only add regret to the picture.
Good luck to you.
Hugs,
Kelly