Not a normal love triangle?

i am a girl and I really like this guy and once we had a talk in which v both declared our feelings. But my parents haven't allowed me to be in a relationship they fear. and then v r unable to date each other.so now he has got his gf but still has feelings for me. (he is also friends with my sister ) so whenever he comes we talk to each other and there is only one wish to happily say that we are together. but I don't wanna break my parent's trust. what should I do?

I would secretly date him