Hi, I'd like to help you with your question.
The amount of stress you have gone through with your health and now having the conflict with family is overwhelming. Being depressed would be a normal reaction for anyone going through such trauma.
You are coping with the grief process as well. You lost your breasts to a mastectomy, you have had numerous health scares and now you have your mother in laws health threatened and a loss of family over it. Grieving your loss is important. Depression is part of the grieving process as well. The depression you have struggled with over the years was most likely triggered by the grief you have experienced.
Have you tried therapy? Talk therapy can make a big difference in how you feel. Although medications are good for treating your symptoms, talk therapy can help you improve to the point of not needing medications because it helps you uncover the issue, work through it and learn to cope with how you feel. It gives you support and provides you with better options on how to respond to your depression.
Talk to your doctor about getting a referral. Or you can search on line at http://therapists.psychologytoday.com/rms/.
You can also work on your depression and grief through self help. Here are some resources to get you started:
The Depression Cure: The 6-Step Program to Beat Depression without Drugs by Stephen S. Ilardi
Undoing Depression: What Therapy Doesn't Teach You and Medication Can't Give You by Richard O'Connor
On Grief and Grieving: Finding the Meaning of Grief Through the Five Stages of Loss by Elisabeth Kubler-Ross and David Kessler
Seeing in the Dark: Getting the Facts on Depression & Finding Hope Again by Gary Kinnaman and Richard Jacobs
You can find these books on Amazon.com or your local library may have them for you.
You can also find a lot of help through support groups, either in person or on line. Here are some links:
By getting support to replace the loss of your family relationships and to cope with your mother in law's and your health issues, you can feel less alone and start recovering again.
Let me know if I can help any further,