I would not do anything right now with your friends. I would call your cousin in law and tell her, in a assertive yet polite fashion, that you called a few people as per her request, but that from this point on if any are interested, they are to contact her, not you. Inform her that you will give her contact information, and would she prefer if she give out her email or her phone number?
If your friends call back, I would say that you were trying to do a favor for a family friend, and now that you have done that favor she will take it from here, and here is her phone number or email to further inquire.
You were more than nice to her about all this. Should she have the audacity to get upset over you dispensing her email and phone, lay it out to her in a clear, assertive, yet polite fashion -- without apologizing or showing any regrets -- that you were asked to help and that is exactly what you are doing.
Consider it a life lesson for her in her young age -- the art of hustling to get your own. Asking someone else to do your job is the fastest way to get fired.
Also consider it a life lesson for yourself -- to find a way to say no and not get trapped into something you don't really need to do. I struggle with this too...but a friend of mine taught to me learn how to reflexively say "Can I get back to you?" instead of thinking about it for a moment and then saying yes. Always remember that when someone asks something of you, they are rarely thinking of you, but rather thinking "how does this benefit me?" Therefore, they are often very short-sighted on what benefit there is for you - if any at all! It is a selfish position that many naturally take. You can protect yourself by reminding yourself that you are NEVER under any obligation to decide right away (unless there is an emergency!) -- it almost always can wait a day or two.