Depression Support Group
Depression is a real and debilitating condition that is often misunderstood by family and friends. Its meaning can range from a prolonged period of sadness to an actual mental illness with specific symptoms. Find and share experiences with others who are going through the same struggles.

I wouldn't put it that way exactly don't go "Its him or me" just say something like. Hi <Insert name here> i can't attend this year. I really want to but <insert his name here> makes me so uncomfortable with his attraction to me. I hope you have a wonderful time.
That's just an example, communicate the issue and let the host know it is not them but someone else.