I don't have chronic depression, but I have spent enough years of my life depressed to know about various effects. One of them is that seemingly 'little' things become huge and horrendous. Someone says something and (probably accidentally) implies something negative about you, and it hurts incredibly deeply. People will then respond with "oh it's not that big a deal" or "don't let it bother you" which is fucking ridiculous. It's not just perception; when you are already injured, small further injuries will have greater impact than they would if you were fine!
It's like depression is having a hand with broken bones in it, when the worst hand damage most people have experienced is a paper cut. And someone is like "why can't you high-five me, it's not that hard!" and sure, it's not much effort to lift your arm and aim your hand at the other person's hand. But you KNOW that it is going to hurt, it is going to cause you damage, and so you say "I just can't do high fives right now." And they get miffed that you're not willing to suffer a little to bring them some joy, because they high-fived you when they had a paper cut. Or someone shakes your hand and you cry out, and people are like "psh, that doesn't hurt, I do it all the time!" Or they tell you "oh it's probably just a hand cramp, I had one before and just needed to massage it out" and they grab your broken hand and start rubbing it! It sounds really obvious in metaphor but people really will try to apply their own diagnoses and then give you their 'cure' when it is absolutely going to make everything far worse.
Depression doesn't just sit in one spot, like disappointment or sadness, because it is not a fucking emotion. It is an illness, and it gets in every single part of your being. It's not something you can compartmentalize. It's not something you can ignore. It's something that has to be managed, and anyone who has been depressed for a length of time is far more of an expert on how to manage it than you are, if you haven't lived it.