I became a single parent for a few years and it was remarkably easy! My child was a very easy child to take care of though.
Think of this--you were the one who got up at midnight when he was crying, you didn't have help doing that, did you? And you handled it just fine.
You took your child on that tennis vacation for several weeks, and did it just fine, all by yourself.
Realizing that you are ALREADY functioning often as a single parent might help you realize that you are stronger than you think.
I think you lack confidence...I can surely understand that, been there, done that.
Since you are a Christian, you may believe that a broken home is a bad thing, and that it makes you a "bad girl" on some level, I know how deep this stuff goes...my mother is a minister.
Just making sure you remind yourself in your life decisions to take the "guilty" part of religion out of it and toss that away. Not sure the negative dogma ever did anyone any good...as with Christianity same with alanon...what's the saying...take what you want and leave the rest....