Difficult phase

We are having a difficult phase that I hope does not last too long. I have heard some people say the halfs are the hardest, meaning kids have the most tantrums and difficulties when they are 2 1/2, 3 1/2, 4 1/2, etc. Ben is just hitting 4 1/2. Some days are ok, but when Tim and I are tired and discouraged, our perspective is that Oliver cries more than 50% of each day and Ben whines and has tantrums more than 70% of each day. And Ben's tantrums are so selfish, which I guess is normal for a child, but so different from his sweet past self, and so discouraging. I find myself not liking him much and I hope I'm not the only parent in the world who has ever felt that way. I hate to admit that I've yelled at them a lot in the past few weeks, which does not help at all, actually makes things worse - creates a vicious cycle, and makes me ashamed. Tim has been more patient than me lately. I really need to reboot and not let myself react to it. Wish me luck and thank you for listening!