It is an absolute lie when you say Christ didn't forgive the people who were mocking Him:
"When they hurled their insults at him(Christ), he did not retaliate; when he suffered, he made no threats. Instead, he entrusted himself to him who judges justly." - 1 Pet. 2:23
You're overlooking what is obvious about the kind of attitude Christ displayed in that moment. He asked His Father to forgive those people because Christ didn't want to be presumptuous enough to think He was as willing to shrug it off. The fact that Christ said "they don't know what they're doing" in and of itself says He chalked it up as them doing it out of ignorance.
Now here's why the Bible says you couldn't be more wrong when you say it's perfectly fine to just express your feelings with no restraints:
"Whoever has no rule over his own spirit is like a city broken down, without walls." - Pro. 25:28
"If anyone among you thinks he is religious, and does not bridle his tongue but deceives his own heart, this one's religion is useless." -Jas. 1:26
And the tongue is a flame of fire. It is a whole world of wickedness, corrupting your entire body. It can set your whole life on fire, for it is set on fire by hell itself." - Jas. 3:6
"I said to myself, “I will watch what I do and not sin in what I say. I will hold my tongue when the ungodly are around me.” - Psa. 39:1
“But I say to you that for every idle word men may speak, they will give account of it in the day of judgment." - Matt. 12:36
“But I say to you who hear: Love your enemies, do good to those who hate you, bless those who curse you, and pray for those who spitefully use you. And just as you want men to do to you, you also do to them likewise."- Luk. 6:27-28, 31
Social media is a toxic hotbed because it is full of carnal-minded people who express their feelings with little or no regard for other people. Human limitations doesn't get to be an excuse for anyone who claims to be a Christian because Christ showed through His own conduct how they're supposed to handle being the target of lawless behavior. If Christ managed to overcome the temptation to retaliate, there's no reason why anyone else who has the Holy Spirit can't do the same thing.