I'm in therapy for this. The biggest thing that I do is truth it out. Yes, you were in close contact but that doesn't mean you'll get sick. If you are healthy, have a good immune system, take vitamins, etc then the chances are lower. My big thing is I never touch my face unless I've cleaned them either with washing or hand sanitizer. And I almost never share food/drinks. There's some breathing techniques I like - in 4, out 4; in 4 out 6; in 4, hold 7, out 8. Try to find a calm environment and listen to calming music. Trust your immune system. Dm me if you want to talk more. I feel for you hun. I would be in the same position.