Help with Family Medical Leave?

Can someone please HELP me with my Family Medical Leave. I like to take 60 to 90 days off from my work due to my health reasons. I have worked continuously for nearly 40 years. My concern is if I ask my employer for Family Medical leave 1) Can he deny this for me 2) If I take the medical leave can my employer terminate my Health Insurance benefits to me and my Family. Thank you for your responses. Any one from H.R can help me with this question. I need this pretty bad.