So, for as long as I remember, I (22F)suffered with separation anxiety. It all started when me and my family moved to another city, and some other hurtful events followed up.  
I always had a hard time going away from home, going on trips ect. And I've always been super protective over my loved ones and had a strong desire to be as close to them as much as possible. 
I am in a relationship for about a year with a great guy but, in about a month or so I have to go away on a trip for about a week.

 I am terrified just thinking about it. My fear is that, while I'm gone, he will forget me , or get mad at me for leaving, I won't be able to contact him or something will happen to him and when I come back he will not be there. 

I'm just tearing up writing about it. I used to go on therapy but can't afford it currently. How can I make myself relax and think more logically?
 I just really don't want to go and I'm even thinking about canceling the trip. 

I'm just terrified that while I'm gone, he will dissapear. Any tips or advice would be amazing..