I need toddler advice!!!

Amy • Single mommy to a handsome boy and currently expecting baby #2!
My 3 year old son does not work through his emotions well at all. He has started this new thing after my brother broke his favorite spiderman toy for hitting him. Well, I told my brother you can't do that and expect it to be okay with him. Broke his heart. This was a month ago, and ever since then, my son son gets angry and he breaks things. Only started right after he saw my brother break his Spiderman toy. Yesterday it was disc one of a cartoon batman DVD, today was disc 2. So today I tried something new. He broke the cd and I gathered up his little bit of Legos he has left and took them outside. I haven't thrown them away. But I'm lost on what to really do to get him out of this hitting/breaking things stage. I have to do something before my 2nd child gets here in March. I appreciate all advice but really prefer someone who has dealt closely and personally with a child like this. He is NOT autistic but has some autistic characteristics, and when he was in birth to three last year, they said that exactly. But he's not in it now seeing as he turned 3. I'm just lost and it brings me to tears seeing him break things. And he didn't start hitting so bad until he witnessed my ex boyfriend fight my brother right in front of my son. I got rid of him fast after I found out I was pregnant this time and he hit my son. I'm just at my witts end. He's also dealing with the loss of my mother still. She passed in June and has been so hard for him to understand. I'm just so lost on what to do!!! Please help!!!