when you get back, head to your local American Legion post or VFW post, there are men there who understand and have been there. and they will listen to you vent and maybe shed a tear or two with you. do not let survivor's remorse eat your guts out. i am hearing a bit of it just in the words you used. there is a reason WHY you are still alive my friend, embrace it, do not question it.
good luck, brother, and may G_d bless you and yours along with your spotter and his family.