If I can provide some advice.I watch a shit load of youtube, mostly people doing things I wish I could be doing. That might not be helping.
it seems like the majority of your thoughts and feelings are negative; that needs to stop ASAP.
If not already, you need to start incorporating things that even for a moment, will take your mind away from these negative thoughts.
For example, strenuous exercise helps bring you to a point of physical pain where you don't think of the mental/emotional pain and as well exercise
gives you endorphins that can bring up your mood even if only temporary.
If you go on hikes start incorporating jogging or running into that; It will completely change the experience believe me.
Find some sort of hobby or find new interests can help keep you occupied and as well can help you uncover some new talents or skills that can benefit you down the road.
Join some sort of clubs or group clubs at your local community centres or something; you need to get out and meet people.
Also if you are on youtube instead of watching videos living vicariously through others there are hours and hours of self-help motivational videos you can watch.
Look up individuals like David Goggins, Jocko Willink, and Jordan Peterson. David Goggins has literally changed peoples lives through his book, interviews and social media presence.
50 is not old. You owe it to yourself to atleast give yourself a chance to eliminate what could be regrets.
It won't be easy but you need to develop some self-esteem and self-respect.
Once you develop self-respect others will notice it, your kids will notice it, your wife, etc. and things will only get better from there.
Good luck