Sweetie, we all backslide. Dont be too hard on yourself.
And Eric is right, you deal with the grief by going through it.
But you can also find ways to handle the low days. It helps to keep yourself busy, keep your mind, busy. Pray, walk, read, join a group, volunteer, pick another project to do at home.
You have to really try each day to have a positive outlook. Soon, after some time, it becomes reality.
You have so much in your life to be thankful for. Concentrate on those.