To neuter or to not neuter..?

So I really didn't want to because I feared that Bruno would change and he has...
He's become aggressive, more stubborn, hard or hearing and now isn't very nice to other unneutered dogs.

I'm really upset.
I feel like I've made the biggest mistake of his life!
He bit me today because we were in my office and a colleague is nervous of him.
He wasnt having any of it.
I held his leash and he just kept biting it and then my finger until he did actually bite me.
I didnt know he cut the skin until he started licking it.
Im worried now...