Don't get discouraged this is a terrible thing to watch a loved one go through and your reaction is normal.. Just be supportive and know that the best thing you can do for him is be there. Talk with your oncologist about what foods but as a general rule stay simple and eat smaller meals. Keeping you and your loved ones in my prayers. We are going through the same thing. He has lost a lot of weight as well. Feels very tired and miserable but hopefully it gets better for him. Don't hesitate to reach out it is a very lonely journey.