Is it normal for my friend to be a douche.

ok so my best friend who ive been close with since 5th grade lost his dad to cancer who I was also close with. I am an avid hotrod idiot. I have a 67 chevy that i drive daily and built up myself. I wasnt into cars until I started driving and had an old gmc and took it to my friends dads often for work, his dad was a very good tech. he also was the person who exposed me to racing and took me to my first late model race. He was crew chief of the race team for 30 years and also started a mess that gave me a hobby and now my career. Life would be totally different without his influence. he passed on a week ago today after fighting cancer for a few years. he was given 6 months to a year when they found it. I have been there for my friend as he has been for me through it all. he was my designated drinking buddy and never drank without me. his mom always called me her second son. the point being we were very close for many years now. I know its to be expected but hes gone insane since. He has been a dick to me and shows up every few days acting strange to me. he goes out with his other friends and seems like he wants to keep me away from whatever they do. we got into it over a girl we both want but that was resolved quickly. He has completely stoped respecting me and my space and my property. hes acting like a 5 year old, breaking my stuff plowing up my yard in his truck tonight,and seems for the past week we will be hanging out and he will just get up and leave. he has to be on the move all the time its very strange for him. He acts as though maybe we arent that great of friends and I feel like he takes all ive done for granted. I always value my friends and wouldnt ever want them to feel like I do or be so pissed off at my idiot like behavior. is all this normal?