Dilema

Help! I don't know what to do. Okay that's not entirely true. I am just confused about what I think I should do. Here is the situation.
I have this friend, S. We haven't spoken since last August. I had to kick her out of my house because she was smoking so much pot she was falling asleep with lit cigarettes. She burned holes in many blankets and my couch and a few of her own shirts and pants. Plus she is very unliked by my parents. As a matter of fact they don't like much of anyone I know.For that matter most people I know don't like S either, so at least in that my parents aren't the only ones. Anyway, my three parents came and kicked her out of my house. I know, I know. When S told my dad that I could have kicked her out, he told her, " no, she's your friend and can't do it." Which was true, I just couldn't bring myself to do it.I knew I needed to but I couldn't.( I know that makes me a sissy, I am okay with that.) She has a problem with prescription drugs and then the pot too, I suspected also crank. Anyway, she went and lived with my friend K for a while and then she left there and went to Whidbey Island. It's a very long story actually. To make it shorter I will just say that I spoke to her probably five times and saw her three times after she left my house. I do care about her very much. I also care about her kids, one of which she has managed to get living with her again. I am sure for the money from C's father. Anyway every time I get to the point where I am not thinking about her or thinking that I need to go find her. Someone calls me and tells me what is going on. I need to make it clear that every time in the past I got the feeling that I needed to contact her, or find her it was because she needed me. I have been avoiding that feeling for months now. Trying not to care. She screwed me over enough and brought enough drama and heart ache into my life. She slept with my husband for christs sake! So anyway. ( I thought I was making this short...) I get a call a couple of days ago that S is for sure doing crank. That she was looking to get some through someone a mutual friend knows. This concerns me greatly and I am glad she doesn't live closer because I would have been over there already. I don't think I need to get involved. But I also feel like I owe it to C to make sure she is okay. You know, just show up and see her with my own eyes. I know C would tell me if she wasn't okay and I know S would let C go with me. I love C alot. She and her sister then sisters spent alot of time with me. C told someone that she was happiest in her life whenever she was at my house. That damn near broke my heart. I want to see her very much. But I am afraid that S will drag me back into her world. I don't want to go there. I am so confused about this. Yes, I know I shouldn't be. I should stay away from her. But I feel it, have been feeling it. She needs me to help either herself or C. I have always been the one to handle such things for her. Get men to leave her alone or break up with her. Find places for her to go, Take her kids for weeks on end. I would love to have C here with me. I have the means to go get her. I have the means for her to contact her dad. I know S will let her come with me. I feel like I am banging my damn fool head against a brick fucking wall. I really wish I could talk to someone impartial about this. Everyone around here is partial to me and wants me to stay away from S. Even Derek who is concerned and cares about S told me that it might be best to not go there. WELL. FUCK! Why do you think I have a dilema. Again I say ( begging on knees) HELP!