Answer:
Between you and me, this chili is too spicy.
Step-by-step explanation:
Despite the fact that "between you and I" is frequently heard, it's grammatically incorrect. "Between" is a preposition, and prepositions should be followed by objective pronouns such as me, him, her, and us. "I" is a subjective pronoun, which is why it is grammatically incorrect to say "between you and I."