I acknowledge the confusion and guilt in you. Lot of questions seem to be coming in your mind related to ways of satisfying your sexual needs. Let me also acknowledge the courage in you to be open about this topic and reach out.
Well, it is not unusual and many people engage in such practices. It can be explained by the term ‘Sexual Fetism’, where sexual excitement and pleasure is achieved by fantasizing or using certain non-living objects. In your case, one way is watching fetish porn, where your needs are satisfied vicariously that is getting pleasure by watching someone else. And the other is wearing female undergarments and masturbating. Masturbating in itself is also a perfectly normal and healthy exercise as long as it is not affecting your daily routine.
Different people use different ways to satisfy sexual needs which is a very natural process. And it is ok to do so, as long as it is not causing distress or interference in the individual’s social, occupational functioning and also the people around them especially the intimate partner. Wondering where do you find yourself?
As far as your guilt is concerned, it does throw some light on you feeling regret which is most important. Exploring ones Sexuality involves lot of experimentation, and you did the same as you say, “Did few things out of sexual curiosity”. It is fine to be on this path as long as it is not interfering with your day to day functioning and other people associated with you.
Hope this gives some clarity!