I'm sorry to hear that. I personally only had good experiences when trying to learn tank or healer (when I was brave enough to go without FC mates), but I also made a point to communicate with my party in the beginning, something like "apologies in advance we're probably gonna die! if anyone has any words of wisdom feel free to dump them on me." There's bad apples all around, but usually the truly impatient will leave if they realize they have someone that doesn't know what they're doing haha.

tbh I don't think you should give up. Find an FC willing to teach you, meet people that can help. Reroll as a DPS for first runs if it'll make you feel less paranoid.