Lie Yue is 3 into her +12. If you heal her for 3, shes down to +7. If 9, shes at +2. 12, at no bonus.
Snake will probably grapple me again and kill me as I only have 8hp left. Reduction 4, so if it does 13 on 5k5, I die.
But, my death buys all of you another round as well, so if you heal her now she can deal more damage. Center on your next turn would be my guess.
But it is your character, play it how you want to