It’s a fake neck line - look at the picture - it had a modesty panel, an extra life of flesh colored material, no skin is showing, it’s meant to look plunging but it isn’t. Jezzzz
So instead of actually showing off too much cleavage, it just looks like its showing off too much cleavage 
OP the shape looks stunning on you, but I'm in the too plunging camp for bridal wear. The top looks more lingerie than an elegant bridal gown, but if that is the look you are going for then go for it, you have the figure for it.