Wow. Your school hands out suspensions for public displays of affection (PDA)?
All I can suggest is that you get your facts straight and also have your friend available to talk with your mom so that if she needs / wants to verify what happened, she can talk to the other student.
The teacher's observations will undoubtedly be on the suspension report, so you'll want to be ready to provide your own version of events and to refute anything on the report that is false or misleading.