As parents we are extremely vulnerable. We wear out hearts on our sleeve and with that we open ourselves up to scrutiny and judgement of others. When we get asked how our day was often we say "yer, yer good" rather than, '"t wasn't great and I'm struggling today".
Most of us will struggle with being a mother or parent at some point, and that's ok. Its ok to say "i'm not ok today and im not sure what to do". Most of us don't actually know what we are doing, often its just a case of getting through the day any way we can and then starting again tomorrow.
The truth is, parenting can be lonely. We can be surrounded by people all day and yet we can still feel like we are alone. Opening up and being more honest means that we can relate with our friends and family on a deeper level which will help us feel less alone.
Lastly and most importantly, telling it how it really is will actually help you cope better. Admitting that you are overwhelmed even when its from caring for the people you love most in the world doesn't make you a bad parent, it makes you normal.