You are only obligated to your husband and family. And yourself. As an adult, you are responsible for taking care of yourself.
Other relationships are just to enhance your life. If they don't, or if they do but at the cost of damaging stress, you need to think of your obligations first. If you have a hard time with your obligations to yourself, think of your husband and family - they need you healthy.
I don't think you can ask others to keep you out of stressfull situations, though. That's up to you. Remember their problems are not your problems. Choose to help when you can and want to, not as an automatic thing. You aren't everybody's Mom, you don't have to always be there for them. Let your "yes" be special and don't let your "no" be a big let-down. Look for the third option - "Here, I'll do X2 instead", where X2 is not what is asked but what you can do without stress. When you can do that, you are helping but people are learning that they can't count on using you. And, frankly, those who aren't willing to enjoy your company on that basis, well, that's not friendship, that's exploitation. It isn't fun. It isn't good for you. You don't need it. You don't owe it. You can't afford it. If you take it, you will fail those who have a right to count on you.