You can totally have turkey breast, offer to bring veggies for sides (measure them out while you’re eating), and have a salad. Or eat ahead of time before going over it will fill ya up and eat what’s on the sheet that’s provided at dinner. I’ve had family gatherings where I have brought my own food so I could stay on track, and nobody took it as me being rude. They all thought I was pretty dedicated and were very supportive. Definitely go spend time with your brother though. I would do anything to get my brother, that I lost, back. You got this! Prayers for your brother.