Bad choices..?

So my friend and I are both 16 and she has started making bad decisions. She dated a guy that felt me up and then he dumped her for her best friend and she had a hard time. She's still friends with his sister and for her 16th birthday the sister offered her weed or ecstasy as a present. My friend vapes nic6 (very low nicotine) and does the occasional shot. To me this is tolerable as she is not doing anything that would be dangerous imo. The ecstasy is a line for me that is crossed. Idk if she will actually take it but idk what else to do. If she does take it, she would be by herself at home w parents downstairs, or with a friend who has already done e. My friend has stuck with me through some absolute shit and she does not peer pressure me so I will not dump her, but I can't tell her parents be she'd dump me