Sad, Unhappy or Depressed?

This picture has nothing to do with the topic..I just like cats.
So..are you sad, unhappy, or depressed? What is the difference? I think I am starting, at the age of almost 65 to figure it out.
The easiest one to deal with is...unhappy.
Happiness is a fleeting thing! And therefore, unhappiness is a fleeting thing as well.
You can say...God..I am so unhappy...my car broke down....my hair is bad.....my kids don't call me...etc etc etc.
But, once the car is fixed, and you see your hairdresser....and at least one of your kids calls you...it's gone..you're happy.
So..we can do away with Unhappy.
So now..are you sad..or depressed? This is a tad tougher. Being depressed can make you sad..and being sad can make you depressed. But...they are not truly one and the same thing.
There is a condition called dysthymia....which is chronic sadness and goes along with depression sometimes.
The difference is...depression can be treated...sadness....deep inner sadness cannot.
So....I have come to the conclusion that I am not depressed...I am just very sad. And..I guess I always have been for some reason. I was diagnosed with dysthymia..which, to tell the truth, is the first time I had ever heard that word. There is no treatment for it. At all.
Most of the time I cover my 'condition' with what I like to call 'humour'.
Some people probably don't find it funny....but..joking around was always my armor I guess.
But the jokes are not working anymore. And I find myself getting sadder and sadder about things that happened years ago. And I find that there are some losses that I cannot seem to recover from at all.
The thing is though...the humour is being replaced now by anger...And I'm not good at handling anger...not at all.
I don't find it funny that my husband is wasting away in front of my eyes..and he is scared and angry....and taking it out on me. I realize that he is very sick.....but I am getting angry at him. I am mad at him. Not for being sick...but for thinking that I don't know how sick he is. For making me feel like I'm nothing..for making me be the 'bad' person. For making me walk around on tiptoes, afraid to offend him...for making me cry. For making me feel 'lesser' than him....
In the space of 15 minutes..he can go from.."I love you so much" to "You are a lazy slob"...
So....am I unhappy....am I depressed...am I sad?
Am I?
Anything?