Star, in my opinion, there is such a wide-range of mental illness, and within each mental illness such a wide range possible from one person to the next...that is impossible for me to say what you should do.
I think talking to your Bishop, or your parents, or in-laws, someone who knows your situation better could be helpful, but ultimately, I think the answer should come down to prayer and personal revelation.
If you decide not to have children, you don't need to tell people anything, it's none of their business. Well-meaning but insensitive people might ask, but you don't have to tell them anything you don't want to. How you handle it will depend on your personality. For example, I might use humor as a gentle way to remind them it is none of their business, "I've asked Santa, but he brought me a puppy instead." You could be more blunt and say, "That's personal." Or you could say, "I have some health issues that make prevent us from having children." They will likely assume you mean infertility. Any of these responses might led the other person to ask even more questions. In that case you have to steel yourself to say, "It's a personal matter," and remember that YOU are not the one that is being rude...they are.