When do I tell my children

I had my lumpectomy on the18th and was able to hide it from everyone except my 4 yr old granddaughter.(She loves to snuggle, which was almost impossible until I told her that I had a boo boo.) Thank goodness she can keep a secret. lol I go back the 2ND to find out where we go from here. I have decided to put off telling my kids until I absolutely have to. My oldest two their Dad dead a week after the oldest first birthday and I was three months pregnant with the second. I wasn't so good at picking husbands and after a 12 year marriage I finally got the courage to leave. Unfortunately we were all pretty damaged when I did. A lot of things happened that I didn't know about because I was always working or going to college trying to give us a better life. Meanwhile my husband was at home making my children's lives hell. Thing is I don't know why they didn't tell me. Other than they say he threatened them. My divorce attorney said she had never seen anyone get a lifetime protection order. That tells you how bad it was. I'm telling you all this because my oldest son said he would never forgive me. His brothers have. He only answers my calls around holidays or if I text him in advance like I did in July when they told me it was cancer and then said it was an abscess. So to me I felt like he thought I made the whole thing up just to talk to him which was another reason why I decided not to tell this time. Except this time since the first of November I have lost over 25 lbs. Which is great because I was overweight but since Christmas Eve I've lost 1lb a day. So I'm afraid it will be soon.