Poor reviews happen.
Maybe you had a feeling it was coming because you've been off your game lately, or maybe you were blindsided by the disappointing marks. Either way, one bad review does not make or break your career.
Performance reviews exist so that you can become a better therapist. If you got perfect marks every time, there would be no room for growth and no opportunity to reevaluate your methods.
Take time to process your review however you need to, but then engage with your supervisor. Ask questions if you have them, and show them that you have a desire to grow as a therapist.
Come up with a detailed plan that addresses tangible things you can do to improve.
If you believe your review wasn't honest, try to not become defensive. Instead, ask for specific examples of what you did poorly and what you could have done differently.