I would not recommend asking people on HN about this. You should seek out a competent mental health professional. These are serious issues, and you deserve competent help.
There are just as many people who give good advice as those that mislead you towards bad advice deceptively on HN. The latter group may actually hold dominance given what I've seen of the structural biases inherent in who gets heard overall.
Useful advice is often removed or downvoted to the point where you don't see it. This is true of all social media today post-AI.
I fully expect this post to be downvoted solely for pointing this fact out, in saying this.
You have a lot of life changes happening all at once. Your support structure is unstable as a result, and this puts extra work on you in cognitive load.
You don't mention how much time you spend on your business, family, etc, but I'd guess its more than half your time for the former most.
Did you take time off for bereavement? (mother, sister, child soon?)
Have you done a bucket list?
Failing to take time needed for changes represses issues, and similar to burnout eventually you crack and succumb to the guilt and stress. Are you sure you aren't just burying your head in work trying to ignore reality?
You can only fix this by bringing the issues to the front of your attention and working through the issues, addressing them in turn. There won't be a magic bullet.
Right now, given what you've said it seems like you are trying to hide in your work. It will only get worse the longer you do this.
Repression has a complex relationship with psychosis, and that's important because eventually if you do nothing people crack.
I would suggest you bring someone on to help running the day-to-day of the business so you can take the appropriate time for these issues. Your business must be a bus factor greater than 1 so you don't have to worry about finances during these tough times.
Your lack of focus is most likely your unconscious mind telling you that you are running away from working on important issues you don't want to deal with.
You may not be able to control the circumstances, but you can control what you do about it.
The focus will return once you've worked through the personal issues. If you are unable or unaware of how to go about working on these things, you should seek competent professional help.
Be mindful though, there are many mental health professionals who are not great at their job or that competent. These people may run you in a circle.
If they aren't helping you within a few sessions and you are putting in the work, move on to a new one.