Oh rollercoaster, I got teary reading your post. I completely understand and am in the same situation ... and also don't know what to do
Just don't beat yourself up over it because that doesn't help anyone. If you can't see them, you can't!

My partner's sister announced her pregnancy (at 7 wks) on the day of my first miscarriage. While she was preg I had another miscarriage and her beautiful little boy was born 2 weeks after my baby should have been (first grandchild too!) That baby is now nearly 1 and I still find it difficult to see him - worst thing is, they live on the same street as us!! My partner spends at least an hour a day with his nephew and I see him maybe every 2 months

On one hand, if you do decide to see the baby, maybe you'll deal with it better than you think. I find I feel ok and can hold myself together while I'm with them but then feel pretty down afterwards. If you can't do it, maybe you could meet with your brother or his gf without the baby and explain it all to him/ her because your relationship with them is important - and it's not their fault. Oh and I send them gifts for the baby quite a lot through my partner which hopefully lets them know that I care, I just can't be there.

You're not alone. And you're not crazy, you're human and sometimes you just need to pretect yourself from pain overload!! Thinking of you