First of all I feel very sorry for you. You have given your 100% but that boy has cheated you. You believe it or not I have also gone through with same kind of situation.
You know life has taught you a very important lesson. Now a days people become very selfish. They react based on there situation. When he needed you he has feelings for you. Now he achieved his goal of life than all his feelings for you got disappeared.
Definitely he will get a better looking girl than you but I know he will never get a better human than you as a life partner. My sister’s marriage also got broken because the boy cleared his CA exam and than these people got another rich family. This is another example.
Incidents which you have mentioned clearly showed that these people are not good. Initially every things was fine but now they found several negatives in your personality!! Great!! What kind of people are they! If these people are behaving now like that you can also imagine that later they can also create problems for you.
I recommend you to leave this person immediately. You are also a good girl who is preparing for UPSC. You are not a weak girl who need help of that person. How dare his father talk to your father like that. Kick these people out from your life and focus on your coming exams. You will get very limited opportunities in your life to appear in these exams so please concentrate.