Depression Support Group
Depression is a real and debilitating condition that is often misunderstood by family and friends. Its meaning can range from a prolonged period of sadness to an actual mental illness with specific symptoms. Find and share experiences with others who are going through the same struggles.

Most of us here have felt or are feeling like you are. Don't let the depression conquer you. I know how week you feel, how tired you are and how pointless most of this seems. Just make it to the next moment. Make it to the next second. And congrats yourself for making to that second, to that next moment. And then try making it to the next. Just concentrate on the smallest things.
And everyone on this board is here for you.
Also I think to help how you feel, offering some time to charity, I would recommend cat's protection league seeing as you like cats - just helping, doing good. This can give you a sense of belonging, give you something worthwhile to contribute to the world, make you feel you are of value and needed.
I don't know why your son has disowned you but I do know that how he feels right now is not how he will feel forever. You have to outlast this and take the opportunity to grow within yourself as much as you can. You have to make your life a thing of joy despite the bad that comes into it, so that when he is ready to come back, you are ready to receive him.
:)