The answer is yes, you do have to mention it and include certified copies of all court and police records. The form states it quite clearly at the start of Part 3:
"NOTE: These criminal information questions must be answered even if your records were sealed, cleared, or if anyone, including a judge, law enforcement officer, or attorney, told you that you no longer have a record."
and:
"Have you EVER been arrested or convicted of any of the following crimes:
2.a. Domestic violence, sexual assault, etc."
and:
"NOTE: If you were ever arrested or convicted of any of the specified crimes, you must submit certified copies of all court and police records showeing the charges and disposition for every arrest or conviction. You must do so even if your records were sealed, expunged or otherwise cleared, etc"
Please read the forms very very thoroughly and attentively. Your answer is right there.
Also, please fill in your timeline when you've filed.