Redefining love in a stepfamily.....

Hey fellow stepmothers!  I have been at this gig for 7 1/2 years now, and I can't say it is getting any easier.  Once upon a time there was a loving woman, mother of four sons, sweet kindergarten teacher by day, who was swept off her feet by Prince Charming #2 just before she became menopausal mama.  Prince Charming #1 had succeeded in stealing her youth but not her belief in happier ever after.  Well, Prince Charming #2 came complete with three darling children.... two little prince-lings and a precious princess.  What a BIG, HAPPY family we would be!  I had enough stars in my eyes to form a new constellation.  A few months after the honeymoon, the reality of blended family life hit like the BIG BANG and those stars flew out into the cosmos.  Now what remains is a giant black hole where my heart once resided.  What happened?  I have been reading other bloggers and found that there is a trend to label  ourselves as Wicked or Evil-stepmothers for the simple reason that the daily wear and tear of "parenting" children we are responsible for but not fully bonded to has a corrosive effect on the heart.  I walked into this marriage fully believing that I was a woman with enough love in her heart for my husband and his children.  But I am having to redefine love as a verb instead of as a warm cuddly feeling.  If I define love as a verb I'm doing fine as a step-mom.....  warm cuddly feelings are hard to come by with 3 challenging teenagers in the house--- whether they came from me or my husband's ex-wife.  How do you define love?