Parent approval

I’ve been keeping the guy I’m seeing secret from my parents-my mother specifically- because I know she and her family want me to marry a Christian. Once I break it to her, it will be a stressor on me from then on out.

But I’ve been with this guy for 4 months now and i want to tell her.

Should I? And how should I break it that we’ve been together 4 months now and I’ve pretended I’m single?