Skywalkmom you are hitting what I found to be the hardest part of the marathon that being a widowed parent is. Fatigue and self doubt was at its heaviest for me in the second part of the first year which is why this section is "reality sets in". None of us had children with the thought we could be doing it alone and now when being faced with the most difficult time of our lives we have to take on so much additional responsibilities.
You can do this, you will do this because you have been given no other choice. It will be hard, you may make some mistakes (I made many) and you may want to quit on a daily basis. But eventually you will find things being more manageable. You will find yourself enjoying moments with your children and feeling happy more often. 3 1/2 years later there are still difficult days raising my kids alone but they are not the majority of my days. Sometimes I still wonder what things would be like for my kids if he was still here but I have come to accept our reality for what it is.
I have never been good about asking for or accepting help and that was probably my biggest mistake. Family and friends want to help but don't always know how and over time they tend to forget what our daily struggle is. Ask for help when you can, it doesn't mean you are not strong, it means you are smart enough to know you are not super human.