Oh my. First, I am very sorry about your husband. That is terrible and a lot to deal with!!! My heart goes out to you.
You do sound like you have your hands full with your little guy. He must be very strong as well. One year old was my toughest age because they are doing dangerous things and yet they are still babylike. It is like you need 8 eyes and 20 hands to keep up with them. The number one goal is to keep them safe and boy, they can make that hard.
Does he respond to the word no at all? I didn't even say no---- I made this "ah ah ah" sound. My kids responded to it, (sometimes . . . lol). They do test boundaries at that age, they do try to get their way, they do unsafe things without fear of consequences---- that is what one year olds do. Whether yours is even "worse" (lack of a better word here)--- I don't know. I would try to stay as calm as possible and think ahead of him about what he might do. Get child proof locks for cabinets, door things so he can't open doors to rooms you don't want him in and baby gates. I made that "ah ah ah" sound whenever my kids went up to the gates----- so mine never tried to climb over. So those worked for us. I put away breakables and had some safe parts of the house that they could do whatever they wanted in. (I have two boys that are 15 months apart). Will he respond to time outs yet? You can get on your knees at his level and look him in the eye and say "no". Keep things really short and simple. "no hitting." Stay VERY calm and don't yell. (or he'll start to be a yeller too . . .)
Now, I have a son that has sensory integration disorder. This is a developmental delay of the nervous system. This child is VERY smart and this has nothing to do with intelligence. But it means he does wacky things. He was out of the box active like your child. He climbed book cases, counters, etc. I stayed calm and kept him safe and tried to teach him. However, by 2 and 3/4 when he went to preschool one morning for 2 hours a week----- a teacher spotted the delay. It was hard for me to see. We had success getting him calmed down at home, but at school he didn't cope well. Whether something like this is going on with your child ---- I do not know. He is still very young. Certainly keep your eye on it and keep reading up on the types of things it could be so you can spot it better as he gets older. But if he does have a delay such as sensory integration, adhd or a disorder such as bipolar---- he will need and deserves even more empathy and patience.
You can always talk to your pediatrician about it. I hope you have someone helping you and get some breaks for yourself. Again, sorry for your loss. Good luck to you.
also, I have to add that his father had a history of bi-polar disorder. He passed away two weeks before our son was born due to a sudden, unrelated vehicle accident.