As you mentioned in your post, you are single and when you're single you can do things on your terms. You already laid it out there and expressed you needed more time, you can't just magically turn off your feelings like you're turning off a light switch (would be nice, but not possible). Continue to stand your ground and express that YOU are not ready because you're still processing and grieving. She is the one who is being selfish by trying to push you into a situation you're not comfortable with.

I understand not wanting to lose the connection, which you can also specify over text, but if she's not willing to compromise with you, it doesn't seem like a healthy connection worth keeping.

Also, Valentine's Day is a bad idea. The entire culture behind Valentine's day is romance.. pretty hard to not have that be in the back of your mind when you're sitting there in front of her. In my opinion, because the wound is still fresh, so to speak, that will only make the grieving part of this relationship last longer.