আপনি don't have to hide it. Just tell him. Then carry on. But ask yourself. Is he the one? Is he the one who is the kind of person আপনি would like to share a long relationship? Does his current relationship look like an unstable one? If your উত্তর are yes, আপনি should wait until he brakes up with his gf, then make a move. At least that's what I would do.
