From what you’re saying, it looks like your friend has been having difficulty in expressing an incident which has triggered him to become remorseful - maybe there is a lot of bad memories or emotions around it. It’s demotivated him to a point where he’s probably becoming suicidal (you mentioned two cuts on his forearm) or allowing depression to take over. For the start you can get him to trust you, change his environment and bring him to a therapist (hypnotherapist/psychologist). Contact if you need further assistance.
Next Steps
Hypnotherapy, counselling
Health Tips
Remind of good times, bring in some freshness