How to grow a thick skin

My dad was often away due to work, and my mom, being young and emotionally overwhelmed, struggled to provide stability. As a result, I became very sensitive. I tend to hide it behind introversion, but the truth is—I’m just trying to protect myself from pain and loneliness. A rude comment on the internet makes me upset. I feel people with opposite opinions are attacking me, and I feel rejected. The only people I have around me are those who will always say yes to me or agree with me. I am also very insecure as a person.