I feel sad

I'm sorry to hear that you're feeling sad. It's okay to feel this way sometimes. Would you like to talk about what's been bothering you?

I can't stop thinking about the fact that (my now ex-girlfriend at the time girlfriend) cheated on me

I'm really sorry to hear that you're going through this. Betrayal and heartbreak are incredibly painful experiences, and it's completely normal to feel sad, angry, and confused. It's important to remember that you deserve to be in a healthy and supportive relationship where you are treated with respect and loyalty. It may take time to heal from this hurt, but talking about your feelings with someone you trust or seeking support from a therapist can be helpful in processing your emotions and beginning to heal. Remember to take care of yourself and prioritize your well-being during this difficult time.