You have my deepest sympathies. My dog Chuck is my best buddy. He was a rescue and we've had him since he was less than 8 weeks old. He goes everywhere with me. In fact, if it wasn't for him I likely would have sold my camp at that time because I was sick of going by myself. He just turned 12 at the end of October. I hate to even think of losing him and I know I will be a total train wreck when the time comes. I am having him cremated as well and he will be buried with me when I'm gone.
You have a rough road ahead for a while and I do not envy you for that. But hang in there and embrace your time that you had together and that Major lead a great life. Keep those pictures of him around. As painful as they may be to look at now, they will become very cherished in the future.