Hello ShyBoldGirl,
well done you for being open and reaching out on PC! You don't sound "selfish" and your description sounds as though your relationship is facing significant issues which need to be addressed.
It struck me when you said you feel as though you are holding two people up. I don't think that's tenable; not in the long-term anyway.
I think for a healthy relationship, both parties need to consider: the YOU, the ME, and the WE. Sounds like part of the problem is your significant other's problems with himself as well as his possible lack of attention to the WE of the relationship. I would not presume to guide you to stay or go. There isn't enough info here and I am not an expert. I would encourage you to seek couples therapy to address the relationship problems with him. If he is not willing to go to therapy, then you would have another piece of info to add to the puzzle. By the way, stonewalling is a risk factor for relationship breakdown...because how can you develop solutions if your other half is not willing to talk/work on them with you?
Something I've have learned the hard way in relationships and find it to be so important:
"we cannot look to others to create our happiness, nor can we create happiness for others...we can develop our own happiness and share it with others"
I don't know if that helps you but I wish you peace and enlightenment.