Lonely

My husband has gone camping almost every weekend for the past 2 months. I like that he enjoys camping and has fun with his friends but I do not like being alone. This wouldn't be a problem if I had friends to pal around with but I just don't. I have my sister in law when she isn't working or running around with her actual friends. It really bothers me that I do not have any friends. I would love to go out and meet people but it makes me ill. I feel I have nothing to offer. I have no real interests I just follow around my husband and his friends like a lost puppy dog. I feel so pathetic and am reminded of how little I have to offer others everytime I am left alone while my husband has fun with his friends of which he has many.
Does anyone have any advice?
How do you meet people as an adult?