Try to prepare yourself
While initially your mind might simply be wrapped up on what points you're going to tell them, it is important to be prepared for how they might react - there are a thousand different ways they could.
Loven explains, "most people either think you are ready to die or you're very sick." To avoid this, you may want to include your current health status in your brief description. Of course, MS can be debilitating and even disabling, but it is not always, so ensure that they know you are going to make it through. With that being said, do not downplay the severity of the disease.
If people react emotionally, let them. You are a special person in their lives and they care about you. So, while it might be hard, try to let them process the information however they needs to.
While some people might react emotionally, the opposite reaction could be possible, and you have to be prepared for anything. Some people might refuse to accept what you're telling them, and dismiss it altogether. Stay calm, and try to understand that this is difficult for them to process, not that they are intentionally diminishing your struggle.