Professionalism concern - really scared about being expelled

So I know this sounds really bad but around a month ago, I made the terrible, impulsive decision to fake my attendance for an anatomy session that I had that day (I'm in 2nd year btw). I entered the attendance code without physically being present at the lesson. I know this doesn't count as an acceptable excuse but the only reason I did that was so I could spend more time studying at home as at that time, I felt extremely overwhelmed and stressed with all the lectures being released and felt like I was so behind on content compared to my peers (I just recently got diagnosed with adhd this year too which has had an impact on my ability to study effectively - I'm still currently in the process of medication titration).

So anyways today, I recieved an email from my Uni stating that they're aware that I've breached GMC guidelines due to falsifying attendance/documents and this is identified as professional misconduct. They've given me the opportunity to reflect with a written response and they've also requested for me to have a group meeting with the Head of Year (group meeting as there are quite a few students in my year who have done the same mistake as me).

As you can imagine, I'm quite scared of being expelled for this dumb decision of mine. This is the only time I've ever done something like this. I wanted to ask for advice on what I should do and what you think the consequences will be.