We have been together for five years till date and then suddenly we have to depart. We are in a distance relationship and I miss him so much it hurts. How do I prevent from hurting myself? (I am not a teen)

Why would you hurt yourself?

How long will you two be apart?

Are you working or going to school?
You stay busy and don't dwell on being away from him.
Why are you now separated?

Because with a normal adult hurting yourself because you are lonely is just not a normal response. You just deal with it,

Where is he, why are you apart, how long are you going to be apart,
What type of contact do you have, skype and/or with video, phone calls, texts