Leaning into vs. trying to kill the boredom/loneliness/emptiness is a strategy. Because this is how it is now. You will only ever get so much love from your cat.

I don't know you and all I know is what you've written here, but it seems like this new situation has unmasked your life and aspects of your personality and the truth is uncomfortable. This is who you were before as well, it's just more obvious now that you don't have the relationship you had.

How it is and who you are: these are the premises of the situation. Now given this, where do you go from here? You decide. The premises are just the start, the conclusion is something else and you're driving the car 100% now.

It sounds like you have the right idea, and this worked in my case. Find what sucks and work to make it not suck and don't expect results overnight. Persist, adapt, overcome.

I sincerely hope the best and that things improve for you.