Congratulations. I'm in my early 70's and have a 2.5 year old.
My son became a single dad, the sole parent to his 2 month old son, and so I stepped up. I had no choice really as we're in the middle of nowhere here. I'm not healthy, have mobility problems and pain controlled by steroids and opioids. But we're parenting him together. (His grandpa is NPC). My son is a great dad, and I'm my grandson's 'mother', sadly the only mother he knows.
It's been a challenge having to go through it all again, getting up in the night, the (mild) illnesses, the picky eating, everything, but it's like riding, bike, you don't forget. This is not how I planned to spend my golden years, but it's been well worth the struggle. I'm bonded to him as I was my own. We're having a great laugh and it's fun giving a little boy the best life. He's so incredibly sweet and I love him with all my heart and soul. I'm right now resisting the urge to post pictures of him, lol.
I first became a mother 50 years ago and the funny thing is I really didn't like babies. I much preferred horses and dogs. You never know what this life is going to throw at you.
I do get a bit sad when I think I probably won't live to see him become a teen. My own boys were such fun teens and I'll probably miss all that.