Oh Guinness! You may say the comments are being heard but this notion of your failing makes me think they're not getting through enough!
More loving 2x4s. Stop seeing yourself as a failure. Your niece does not care that she doesn't have Guinness cousins. She has YOU. And you have you too!!!! Don't discount that. Are people only valuable if they produce cousins in the world? What kind of weird Orwellian Dystopian society would that be?
Please learn to be kinder to yourself! Who does it benefit that you feel this way? Not you! Not your family! Not all these poor impassioned SI members trying to get through to you that you have value just as you are!
Look in the mirror and say: I have worth. I am not a failure. I can still make a good life for myself. I DESERVE a good life and am capable of it.
Can you do that for me? Can you love yourself again? What if you were looking at your niece and she said she was a failure. Wouldn't you want to comfort her? Can't you extend that kindness to yourself?