I think the “heavy price” she talks about could be because she knows her wedding with SML is probably not going to happen. Her reputation could be affected, and she may even end up having to become a nun.

And mind you, at this point she is still jealous of ML seeing him with the new villain lady in red, because she has no idea yet that ML will actually end up being with her.

Then there is the line, “I really can't let go.”

On the surface, it sounds like she is talking about her revenge. But I actually think she is talking about Shen Run. She can't seem to let go of him, even though she knows they are now standing on opposite sides.

And that makes the conversation with Grandma Chen even more heartbreaking She may be questioning the path she chose, but perhaps what she is really struggling to let go of is the person she never stopped caring about.