Positive stories about kids and step parents

Can anyone tell a little story about dealing with step parents? And how close they are with them.

I’m having tons of anxiety right now, me and my husband are separating and we have two little ones. I can’t imagine marrying again and having the new guy in my life loving my kids as if they are his own. I know there are bunch of other people that do but I just can’t see it. I just want my kids to be loved and to have a strong family unit. I’m just so scared. I want to my kids to think I failed them because I’m not with their father anymore. I always imagine to marry only once and to have a beautiful family. It’s killing me that i won’t have my family together anymore.