My W is undergoing breast cancer treatments right now. I've offered several times to help her, offered specific things like to mow her yard or get groceries or do laundry, whatever she may need. She's refused it, and that's fine, it's her choice. But that didn't stop me from offering.
I see her about once a week when we switch kids and I ask how she's doing, how the treatments are going, how it makes her feel, etc. That too is support.
She posts on CareBridge and I post uplifting messages for her there now and then.
I don't know if any of that helps my sitch, probably not, but that's not why I'm doing it. I'm doing it because regardless of our sitch, I want to be there for her in some way during this difficult time, and that is being true to who I am. I'm not saying you should do the same, I'm just saying that even if your W doesn't want your support you can still offer it if that's being true to who you are.