Oh wow totally missed this. Really sorry to hear that Tom.
No words to describe the feeling of losing a close parent. I can only express to you that I know how it feels and it's a loss that is felt each and every day.
But think of the wonderful times and those times when you look back and go, "Wow how the heck did she put up with me doing THAT?" Laugh instead of cry, smile instead of frown, keep her memory alive and she will always be with you.