Ask any person who masturbates on their own in secret if he/she feels guilty afterwards and I bet he/she does. I don't think the dressing is a big part of feeling guilty, no more than say using a vibro or looking at sexy pictures.
From early childhood we are taught not to touch ourselves in those "private places" it's dirty or naughty. When we do, of course we feel guilty.
Nor do I think that anyone who wears clothing (male or female) simply as an aid to masturbation is a crossdresser. Most people have some "aid" to sexual pleasure, clothing is just one. Would we call someone who uses a vibrator to help them a "Vibro"? "Oh did you know that lady is a vibro?" Of course we wouldn't, so why call someone a crossdresser just because he/she likes to get it off in a few bits of clothing?
I'm not indicating here in any way that you are or are not a crossdresser and I'm sorry (admin) if I drifted of the plot a little, just delete it and reprimand me if I have.