2 great links BTW
Khalid Yasin makes some great points.
Just would like to add my tuppence worth. Firstly sister, as a fellow sister I have to inform you that this stuff goes on & you just have to ignore it. Maybe I'm saying this, because I'm older & you realise certain things go on, not nice but true. If you're having problems with it, I suggest you make sincere duah to Allah SWT that he gives your bro guidance & that he makes it easy for you to accept, & forgive your brother & rebuild your good relationship with him for the sake of Allah. Just remember, if Allah is all forgiving & most merciful... Then who are we NOT to forgive?
I do not think that you should go to your Parents at all. You're angry & upset. I think you have to be mature about this. If you have already... Too late, I dread to think what happened.
Personally I think your bro just needs to get married. End of.