I'm not sure there's one way to do this - it really comes back to you.
It's loving to send clear and consistent messaging, so I might start by considering your sister's POV and how she would take it. Would she appreciate hearing from you in a reasonable, "My sister was thinking about me, and I know she also needs space right now" kind of way, or would it cause confusion for her?
After that, I'd probably consider what I wanted to do. It's important to uphold our own values in the midst of boundary setting - is it critical that you reach out to family during the holidays? Is that a value you hold high?
It's not always cut and dried, but I admire that you're considering the consequences and reaching out for help. Trust your gut - whatever call you make, there will most likely be consequences. Make sure they're consequences you can live with and navigate in a way that leaves you respecting yourself.
