I feel used by a guy I like and I'm bitter
What did the guy do that makes you feel used and bitter?
He has been so careless in our relationship. And never accepts my help.
It sounds as if you are being manipulated and groomed by this person. He is definitely taking advantage of you and that is not right. He is wrong for using you like this and you shouldn't become his victim or you will develop mental health issues.
He's not wrong. He was troubled and I was nice to him. I just want a normal relationship.
I am sorry if this is coming as a shock to you. You can tell him how you feel but I don't think things might work out. If they put that much effort in I doubt they would not stop playing games now.