Sadly people think its okay to act like trash because there are screens and potentially thousands of miles between one another. I do agree the block button is useful, to a point. It's much different if you had developed relationships with people online and became their friend. Especially if you sought some sort of company or comfort online. You choose to give a more significant level of trust and vulnerability in others. Reality isn't so kind and people can and will take advantage of someone for whatever reason they want.
OP, I don't know how much this applies to you, but if I have any advice surround yourself with people who are chill and don't display red flags. When you meet a person, and they have a red flag, cut them out. Based on my own experiences, I'd watch out for:
• People who are often always involved in some sort of drama, and make it routine to complain about petty shit.
• The person who always routinely talks about others around you. Chances are, they'll talk about you too.
• Someone who complains constantly about negative stuff, not venting. Someone who vilifies others for what they like, dress, talk, ect. when it's hardly warranted.
• Realize you will go through many online friends and people change. You'll probably notice a lot of people are just fucking assholes.
Sorry you feel like you do, but for now maybe this could just help nudge perspective.