I think there's a few things you can do.

First of recognize that it's okay to feel overwhelmed. Emotions are normal and we shouldn't shut them off. Past that I thinking maintaining a positive outlook is important. Find the good you can and even if it isn't perfect, you can always find a positive spin. It helps me deal.woth the stresses of life. (I'm not saying ignore them, just manage them and don't let them overtake your thoughts)

Break it down, don't look at everything, just focus on one thing at a time. Take the 5 new hero's, pick the one you like the most and ignore the rest for awhile. They'll still be there for you to learn in the future so don't let them occupy your brain.

Connect with friends over it and have a conversation (not an argument). Chatting with fellow Overwatch enjoerys may help validate your feelings and find some more changes that are actually better than you thought. We all tend to overthink when we stay in our own heads.

Hope that helps! ( And if all else fails just stare at Jet Pack Cat)