I definitely hear what you're saying with the Marine Corps. Are you currently active? I didn't know that part. If you are, that does change a lot. I would say you could be more open in your personal life, but as a marine, your personal life is usually very closely entwined with your job. I just hope you have at least one person you can confide in and who you don't have to pretend with. Everyone needs that, regardless of whether they've gone through something like this or not.
As far as being a failure and not a man, I totally understand why you feel that way (because this f***ed up society has told you to feel this way). Please don't take my posts as arguing with you or telling you how to feel, and if I'm not being helpful, please let me know. The last thing I'd want to do is make you feel worse. I am just trying to give you a different perspective from someone "on the other side" of the situation.
Women are all different and you are right in the fact that many women want a protector, but... you're a Marine. You have protected ALL of us. What happened with this sick woman can never erase all of that.
Not all women are shallow enough that all they want is a protector. What I'm saying is after some time has elapsed and you gain some of that confidence back, and the right person comes along, if she is the right person, she will understand. She won't just see the assault, but she'll truely see you for who you are. You are a brave man who's sacrificed so much already to protect her and her country, who had something terrible happen to him. You may feel like an emotional wreck now, but it won't necessarily last forever.
Of course you don't want to be touched by a woman...this just happened to you a few weeks ago. Give yourself some time and some credit. Look at what you're doing right now. You've told someone what has happened by posting on this board and taken some of that power back, instead of self-destructing...that takes a strong person. You obviously love being a Marine and you're willing to sacrifice your emotions to keep that honor...that takes a strong person. Of course you feel vulnerable and a failure, but this doesn't translate into who your really are.
I have a close friend who's ex-army. He was deployed to Iraq multiple times as and infantry man and has severe PTSD. Even though he's no longer active, he was still ashamed to tell anyone. He's had multiple surgeries to remove shrapnel from his back and has trouble holding down a job from the constant flashbacks he suffers.
Something similar to what happened to you, happened to him as well. He was trying to deal with his past war demons and made a mistake which led to a horrible experience. I would never look at him as any less of a man. He's a hero and I would do anything for him. Things have been extremely tough for him, but he's in college now, got his own place and is learning to live life on his terms. Now that some time has elapsed, the flashbacks have lessened and he's gotten most of his confidence back. He's a strong and amazing person.
I know you can do it too and I know there are people out there who will understand what you are going through and not judge you. Give yourself time to heal. You are a man, and you are human too. Again, you have to live life on your own terms and only you know what is best for you. I think you are doing an excellent job in coping and admire your strength. Hang in there.