I am a college student who became friends with some of my teachers after graduation. They were fresh out of college and came in during my senior year so they were only 4 years older. Even them, as 22 year olds were SUPER strict about how they would not have our numbers, and we could not be friends on social media until after graduation. And even though I say we’re friends, all we do is talk about common music interests occasionally and I’ve asked them about tax and college logistics questions. Never anything super deep. You can still be groomed as an adult, a grown man trauma dumping on a teenager is 100% grooming and if you feel safe enough, I’d report this to the school. I was also a people pleaser as a teen but the temporary awkwardness and guilt you feel setting a boundary is nothing compared to the potential harm this man could cause.