New to this

Hello. My mom was diagnosed with Stage 4 colon cancer with metastases in the liver and lungs back around Christmas 2022. Surgery was not an option due to many fistulas and cancer in her pelvis basically “sticking” everything together. She has been on chemo every other week since her port placement in January. Started with oxiplatinin and 5FU pump until she had an allergic reaction during her 7th treatment to the Oxi. Then she was put on irontecan and since 5FU is in a nationwide shortage, she was put on cacecitabin pills as a replacement. She does not tolerate the pills well. We are now getting ready for her 5th or 6th scan to see how everything is doing. The doctor wants to put her on Avastin but says that as long as she has fistulas it is too risky and the Avastin can cause a perforation. My mom has been doing well with very little side effects up until this most recent chemo. Mentally, she doesnt think she can handle anymore and I dont know what to say to her. I know that long term chemo or some kind of treatment is in the cards and I dont want her to feel discouraged but how do I keep her mindset positive? She is 66yo and retired 2 months before her diagnosis and now feels like cancer rules her life. She refuses to speak to a therapist or social worker or even a support group because she feels she has enough support at home. I am scared that she wants to “give up” but also know that ultimately its her decision? I feel like she has so much more life to live but she feels hopeless. Any advice would be appreciated.