Firstly, this is not the end of the world. Being diagnosed with a chronic condition is hard news, and IC is a lot to take in at first. Doctors will throw a lot of information at you, including the diet. But, IC is like a rollar coaster with flares and times with manageable symptoms. While it often feels like the pain will never end, there will be days that life will be mostly ok. You will learn to control your diet, your routine, and find products that you like.
Secondly, learn to manage your embarrassment about the condition. Become comfortable with words like bladder and urine. They are not dirty, they are the clinical terms. If others find them icky, that is not your fault.
Lastly, embrace those who love you and support you and let those go who do not. You will learn who your friends are by who is willing to stay by your side as you are forced to change. Don't worry that some people will drift away from the new and odd life that you lead. You don't need added stress - it is bad for IC.