Hello lokisgirl49: I see this is your first post, here on PC. So... welcome to PsychCentral... from the Skeezyks!

At 16 years of age, your brother's male hormones are raging! This may be nothing more than him not being able to control himself... yet. On the other hand, his actions are completely inappropriate! Do not spend time with him in your bedroom, his bedroom, or anyone else's bedroom. Continue to maintain a respectful distance from him in other areas of the house. Let him know, in no uncertain terms that there are boundaries he must not cross. And then enforce those boundaries without exception.

Sooner or later, you may have to discuss, with your parents, what is going on. I know you wrote that you & your brother have been close & you don't want to ruin your relationship. So, perhaps you don't want to involve your parents right away. However, if this sort of behavior continues, or even escalates, it may be necessary. Don't wait too long. I wish you well...