Can I recover my iMessages I unfortunately deleted?

It depends. If you are using iCloud Messages, no. If you are not, then if you have a backup of the iPhone that was made when the message was on the iPad and you have not made a backup since the message was deleted, you can restore the iPad to the backup. Understand that restoring to a backup takes the device back to the date/time the backup was made and anything done since that time is lost.