I know the loneliness and fake veneers. You feel isolated, and the depression just makes it worse. You feel the pain but because no one else can see it, you feel more and more distant. It's ok not to be your normal self when you're in pain. Seeking support here is a good step. It will help you get the support you deserve and I hope it can help make you happy again. You won't feel alone forever. It will pass one day. It's hard because you don't know when you'll be better, but just because you can't see where you're going doesn't mean you're not going to get there.
One thing you need to remember is no matter how distant you feel from you children they will ALWAYS ALWAYS notice when you're gone. Your children love you, and if you die it will traumatize them. Seeking help on here is a good sign, it shows that you know you're supposed to live. Please don't act on your feelings. If for no other reason, live to save your children from the depression you feel now. They love you and they WILL miss you. Distance can be closed. I know it feels lonely now, but there will be a day when you're closer.
I've never been married and I don't have children, so I don't know what exactly you should do about your relationship with your husband, all I know is that it sounds like you won't be happy until it changes. You aren't "supposed to be happy," as you said, because you're not in a good situation. Part of my depression stems from my father verbally and physically abusing me, and I think it's similar. It's hard when it's family because you can't just cut them out of your life, but I strongly recommend doing something about that relationship. You deserve to be happy and no one, especially not someone you love, should be allowed to take that away from you.
I sincerely hope you find a way to fix the things pulling you down. Now that you're part of this community, you are not alone. People on SF are here for you anytime.
Also, unless you didn't mean a word of what you said, you are not wasting anyone's time. You have every right to share. I read the post because I wanted to, I replied because I wanted to, and I want to help you because I want to. :console: