I think there are a couple questions you need to ask yourself - the first is why is it hard for you to be alone? You're the one person you're stuck living with for your entire life - it shouldn't be hard to be alone with yourself. That's where it began. That's where it will end.
You mentioned you have a therapist - this is something you might wish to explore with them.
The second question is related - what are you looking for in the "not alone"? What do you want? What would bring you peace? Are you looking for a relationship? A friend? Sex? etc? While you have to be comfortable with yourself, part of that comfort is knowing and being confident in what you're looking for. It may be that the world won't or can't provide it, but that's why I put this question second.
The final point I'll make is that there's nothing stopping you. You're an adult... within the constraints of the laws of your society, you CAN do what you want and there's nothing stopping you. It may not go the way you want, but it might, and wouldn't it be fun to try?
I like being alone. I'm good at being alone. I was an only child, often left alone , and I have lived alone (although dated a lot) for 20 years. But if you put me in OPs situation, it would easily be tough. Working from home, living alone, totally lost your social circle possibly, AND sad over a recent breakup probably. Thats a prime recipe for problems even for people that do enjoy being alone for the most part.