I’m going to go against the grain here, but I think you should tell your children how you are doing.
I grew up with a single parent and she has had some very dark times with depression etc. She protected me from it as a child but as an adult she is much better (because I made her) at telling me when things are not going so well. I speak to her most days or message à bit. It is not a burden. She is not a burden. She gave so much and sacrificed so much that it costs me very little to make sure she isn’t lonely and that we have a bit of a laugh every few days. I enjoy having a relationship with her now that is more of a friendship.
I was quite selfish and self involved in my 20s (as most of us are!) and it took a bit of a crisis to wake me up.
You know what would have devastated me as a daughter? If my mum had killed herself while j was busy working and partying. I don’t know that I would ever have recovered from the guilt of feeling that my mum couldn’t tell me how she felt.
Please tell them. It will upset them, of course, but that would pale into insignificance compared to how they will feel to know that you didn’t tell them. They will assume that you didn’t trust them or, worse, that you didn’t love them enough. I KNOW that isn’t true - your love for them fills every post you mention them - but I’m giving you my take as a daughter who was once similar to yours (different career, but very much into my own life in my early 20s). Im much happier now though and my mum is doing really well despite semi-shielding as she’s in her 70s.
I promise you: telling people you love is better than not. People looked at my mum as the strong tough business woman who didn’t need any help. She enjoyed being seen that way and it made her feel strong in theory, but it was also incredibly lonely and miserable. She was scared of being seen as vulnerable but she is so much happier and better connected since she let down a few walls. I know it can feel like it’s the last scaffolding that is holding you up and that if you tell someone you love either it makes it real and/or that sense of the last bit of scaffolding will collapse, but I promise that it’s more like ripping off the ivy that’s choking the tree or crawling into the house: it might uncover some vulnerabilities but you can’t start treating the tree or repairing the house until the ivy has been brought down.
I hope you are having some sleep right now (my cat has just woken me up because the neighbour’s Maine coon is outside our bathroom window so mine is yowling. He has a new thing where he gets so wound up that he gets bilious and rage-vomits on the carpet so I’m trying to get him to come away from the window)