If the same as in the OP photo, it was correctly identified as Duranta erecta and very likely the cultivar 'Sapphire Showers'. It is subtropical in origin and will not survive a New England winter in the ground. Rated to only zone 10 but can take a light frost.

are you otherwise in india??? be nice if you could add your location to your Id name ... like the rest of us ... when you said you visited.. i presumed you left india .. but another post seems to make me think otherwise ... ken

Silene armeria usually has its flowers in multiple clusters. This plant has single blooms? It looks like maybe there would be small clusters if the other bud stems weren't drooping down. I have to question if there could be a problem with the health of the plant. It's in a very small pot, and I think silene roots run deep. Usually when I buy these plants they come in the extra tall pots to accommodate the roots. Can the term in situ apply to a plant in a pot, or just to one that's growing in the ground? The plant does have a beauty to it, in a slightly tortured kind of way.

Unlikely to be excessively aggressive here in the PNW. Wants full sun and very good drainage and minimal watering after establishment. I grew it in my beachside garden and it was easily manageable. Just dig up any shoots that stray too far. It is a big cheerful plant (to 6') with those large tissue paper-like flowers. Actually, here propagation is not all that easy as it resents any root disturbance and is difficult from seeds. They need scarification by fire to germinate. But a small, well-rooted start should take well.