They aren't fooled.
There is way too much here that suggests that your family probably knows a LOT more than you think they do. As you said, your mom knows.
Your dad probably knows but is in denial mode. Your brother probably suspected, which is why he went into your room, and may even want to talk to you about it. Don't shut him out with lies.
You obviously enjoy dressing, and you seem to have some transgender desires as well. At this point, your family is probably assuming that you are like Bruce Jenner, and are wondering if you are suffering the same way he did. The mask is hard to keep up. You have to shut yourself down emotionally, sexually, spiritually, and keep friends, family, and other loved-ones at arms length.
Take the time to talk with you mom and your brother, now that they already know. Ask your mom if your father knows anything and how he feels about it.
Once you are free to be you, you can start to really explore where you want to go from here. if you could have a wand that would change you from the guy you are now to a reasonably attractive woman who would always be accepted, would you change to a girl and break the wand? Would you change to girl only for the week-ends? Or would you change to boy only for work?
You are transgender, but probably NOT someone who MUST transition. On the other hand, you have spent up to this time in your life being forced to hide your clothes, your wig, your feminine behavior.
If you no longer have to fear rejection and hatred of your family, would you still want to spend most of you time and life "drabbed out".
For some of us "drab" is "DRessed As Boy" vs "Dressed As Girl" (drag), but it's just a statement of our wardrobe of the moment. For others, Drab describes not only the wardrobe, but our existence when we wear that wardrobe.
Let you bother and mother know that you DON'T plan to transition AT THIS TIME. You don't even get out of the house. They may have found your "stash" but were afraid to talk to you about it. They didn't want to scare you or threaten you.
