What a great question this is. I know that this is something that so many women today struggle with, and I myself have fought this battle more than once in my life. I cannot claim to be an expert, as I do not always feel like I have overcome this, but I can share with you some of the things I have learned in the process of seeking this answer for myself.
I look back and remember when I was 19, and I gazed down at my newborn son, scared and wondering "how am I going to do this alone." That is where the mission began, the mission to find someone to fill in the space that was missing in my new family, or so I thought. Looking back on it I realize now that I was looking for someone to fill what was missing inside of me. I mean this is how I ended up pregnant in the first place wasn't it? Thinking what so many of us think today, that the affection of another, the attention and the physical wanting of a another were what defines our worth. I was seeking love and acceptance, and would pretend to be anyone or anything to have it. It was the only thing that filled the emptiness, at least for a while. Relationship after relationship, it was always a disaster, and in my mind it was always "their" fault for messing it up. I just wanted them to love me and appreciate me. I was looking for someone to complete me. What I have come to realize is that no one is really up to that job. It isn't a job for someone else. This was my problem, and I was never going to have a healthy relationship with anyone until I fixed me. We cannot depend on others to fix what was broken before they got there. Being a single mother, it is so easy to do. We are looking for that complete package for our children, the happily ever after. What I found is the best thing I could do for myself and my children was to learn how to complete ME. How to appreciate ME. To show affection and compassion to ME. To find a power greater than ME to place my burdens on, and instead of finding a man to fall in love with, I realized that I needed to fall in love with myself, and my kids. I found a strength that I never knew I had and with that strength came a peace I really didn't know how to handle. I was so used to the drama and the chaos that I couldn't stand the silence. Until I realized, those were my moments to refuel. I would write in my journal about all my frustrations and feelings and that helped me sort through and reflect so that I could make changes in my living and in my thinking. I was running around looking for someone to tell me who I was for so many years that I never realized that I needed to introduce myself to ME and discover how valuable I am. When you can get to this place, the loneliness and need for someone to define and complete you, well it fades off into the distance. Then, when you least expect it, that person, the one meant to walk WITH you, (instead of the one you were looking for to carry you) will appear, because you are finally in a place to receive the gift of companionship, instead of suffocating in codependency.
So my friend, there is my walk with the struggles of codependency and single parenting. I hope they can point you in the right direction for your journey...and honestly, I never REALLY felt grown-up until I surrendered to the process. You will be amazed at the strong, independent, confident and beautiful woman that is just sitting under the surface waiting for you to peel of the layers of fear and doubt....and just remember when you feel overwhelmed, Breath! We are never given more than we can handle.