This question seems to be incomplete. However, there is enough information to find the right answer.
Answer: No. Although we can understand that Denny feels betrayed because Rita was hiding the fact that she was still on the pill, he´s not justified; she is.
Step-by-step explanation:
In the play "Educating Rita" (1980), by Willy Russell, Rita´s hiding from Denny that she was still taking the pill was the only option Denny had left her because he was pressuring her to become pregnant despite her not being ready to do that. Denny´s actions (becoming violent and make Rita choose between getting off the pill or moving out) are those of someone who is not willing to accept anything but what they want, regardless of other´s feelings, and that makes him feeling betrayed unjustified.