The first is correct. The second is incorrect.
Here, the word "tell" means "to say to [someone]" with a focus on "to [someone]."
I can "say" anything at any time. I may have a person or people listening or reading, but it is not necessary.
To "tell," we must have someone listening or reading (or we must believe that we have such a listener or reader).
If you want to use "say" with "me," you must include "to":
Example: "How could you say that to me?" (This shows that someone is surprised and sad or angry about what was said. It is rhetorical, which means it looks like a question, but no answer is expected. It acts as a statement (i.e., "You should not have said that to me.")
Another example: "What would you say to me if I were in your shoes?" The idiom "in your shoes" means "experiencing the same circumstances [as someone else]." This is the same as asking "What would you tell me if I were in your shoes?"
So "tell me" and "say to me" are almost the same. However, a native English speaker would never ask someone to "say to me" something. We would use "tell me"; or we would use "say" alone (e.g., "Could you say that again, please?")
"To tell" focuses on the listener or reader who will receive the message. "To say" focuses on the speaker or writer, or on the message itself.
"To tell" can also mean "to show" or "to perceive what is shown."
Example: "Only time will tell." (This means that time will show us more, or that we will learn more after a while.)
Example: "I can't tell if you're mad at me or not." (This means that I do not see any signs whether the other person is angry or not angry; they are not showing me clearly with their face, voice or actions.)