Answer:
- Mi novio me las dijo.
Step-by-step explanation:
The correct way of using both direct and indirect object in the sentence "mi novio dijo muchas cosas a mí " would be the sentence "mi novio me las dijo".
-The sentence that says "mi novio se las dijo" is well written however the pronoun "se" can't replace the first person.
-The sentence that says "mi novio me los dijo" is well written however we require the plural pronoun "las" to replace the phrase "muchas cosas".
-The sentence that says "mi novio las me dijo" is not written very well because here there is a word order problem. It should be "me" and then "las" but not "las" and then "me".