Wow, you have had a few things to deal with. You are a very strong person for dealing with what you have in the past. I also have OCD and have fears of dying like almost everyone with the disorder but you are the first person I have heard of to be that afraid of lightning. I think it is normal for people to stay indoors when it's storming for fear of being hit by lighting and I understand that your fear is much more intense. The thing I want to say to you is that YOU WILL NOT BE HIT BY LIGHTNING!
I don't know if that will make you feel better but I thought it was worth a try. Good luck and stay strong! You are not alone.