Welcome to the forum
If you want "and they all lived happily ever after' this is NOT tghe series for you. It is not a "light" series. What to say without giving you spoilers? hmmmm.
The Red Wedding, which you refer to in your post, is the single most emotional event I've ever read in in fiction. I guess you could call it depressing, for me it was just amazing writing. Although the rest of what you can read now- whatever you haven't read in ASOS and AFFC will contain material which might also be "dark", nothing else in the series or in fiction that I've read compares the TRW.
So I guess it will get "better". I can state the obvious and say that GRRM is not killing off every major character in the series. I can say that AFFC is considered by many to be not as good as the first 3 books, although it is absolutely worth reading. You may just find the first 100 or so apges ummm, hard to get into? boring?
You've stuck it out this long, my advice would be to finish ASOS and then reconsider as to whether or not you want to continue. I think you'll ultimately be glad you continued, if you do. The first 4 books are the best fiction I've ever read, in any genre.
Let me finish by saying that I hate deaths in books or movies. I still am bothered by Jack London's "Call of the Wild", which I was forced to read in school. I had tears in my eyes yesterday at the end of Voyage of the Dawn treader. The have been Star Trek TNGs that have made me weep. I HATE animals getting killed in particular. I also like it when my entertainment makes me feel something, forces me to think about thinks in ways I haven't before, teaches me about things I iknew little or nothing about, allows me toleave this world for a very different one, albeit not necessarily better.
Ignore what I said above. Read on, suck it up, it's going to be worth it. I could have saved myself a lot of typing by saying just that