Are you in therapy or on medication? That should be the first step, i know it is a hard step to take, but it could really help you. If you want to make sure your kids don't go through the same thing as you went through then you need to get help so you can improve how you feel and that will help you enjoy being a mother again, because these years will be gone.

I don't really suggest talking to them about how you feel just yet, not until you have talked to someone professionally, and depending on how old they are they may not fully understand. It isn't there job to have to worry about this or deal with this, so they shouldn't have to change or have to worry too much. One thing you don't want is to explain you are depressed or sad and they blame themselves. I did this a lot as a child when my parents were upset. Which is why I suggest talking to someone first about how to approach this, or maybe family therapy and individual therapy, or have you done that?