I'm going to treat my girlfriend like this
How are you going to treat your girlfriend?
Life is made out of pain, if she doesn't goes through the pain with me, she doesn't deserve me
Your girlfriend should be treated with respect and utmost kindness. She doesn't deserve to suffer in this relationship. It is wrong to abuse your partner's wellbeing. You need to love her properly or break up with her if you have nothing positive to offer her.
I read it somewhere saying that if a girl has tattoos and piercings that means she's willing to endure pain.
That's quite the judgement you're making. It sounds like you are unable to show a mutual respect and care towards your loved ones. People want to be treated with compassion and dignity in their relationships, if you offer them that, then you'll feel more satisfied in your own relationship.