I m Married but in other relation now...?

I m married with two kids.... Now I m madly in love with other girl who know each nd every thing abt me. It's 3 year old relationship...God knows hw it happend...I swear I can'nt live without her nd same is the case with her. My family has no clue about my relationship.... I KNOW I AM A CHEATER.... But I can'nt help it... One single clue to my family nd my family life will spoil.... I know all this but don't want to spoil my family as I m also emotionaly attached to my wife nd kids....Also It's really painfull to get out of my other relationship.... I feel really helpless... I know only God can save me....nd there is no answer to my problem except few of u can suggest me to get out of other relationship nd save ur family..... Pls suggest how I can keep both the relations without hurting anyone out of this.....Now it's ur turn...Call me Cheater, Stupid, Person looking for lust.....but that's ur point of view.... but I m in Love......why a married person cannot fall in love ...why...why...For God sake help me.....Help !!!!!!