Should I feel better with what my cousin said? I am worry I will die young or get sick again since I had cancer when I was younger ?

Spoke to a cousin that’s gifted I asked if I will live a long life she said to stop thinking this way that I’m gonna die take it day by day don’t worry about things you can’t control and I also asked if she feels I would ever get sick again and she had the same response. She also said I’m young and pretty have a lot going and to keep focus. I told her I asked my boyfriend if I die if he would move on with someone else he said he didn’t know that hurt me put me in more fear. I kept telling how I’m so scared she said I have to really get my feelings and thoughts control and become stronger because I am contemplating my future! I said would I live to see my 40s & 50s she said again to take it day by day get stronger with myself and my thoughts that’s what I really have to work on and I asked would I have kids and see grandkids And she sounded like she didn’t know what to say and then said you’ll be old like me ok and feel old like the rest of us and laughed