This morning when I was about to feed the birds, I found one of my female birdie was hanging on a string, she died already, I raised her and saw her grow into adult from egg....

I don't know where the string come from, I NEVE put string to my cages or birdhouse. Must be my mom who accidentally or placed one inside when tight the veggies few days ago, which this cause disaster for my birds. I saw her suffered too much and bleeding from neck area because that's where it got tight up and hang her in the air sigh. I found out it's the bird I tried tame her before when she was fledgling stage 3 years ago, I had her for 3 years and now no more seeing her.
Her mate was crying by singing whole morning today, I am sure he is calling her but I feel sad, is he going to stress out these days? Since he play and with her 3 years ago too

I don't want to hear him crying and calling her with singing voice all the time, he usually sing only when he is happy with his mate- the one just died this morning. Any suggestions I can do? Should I put him into hospital cage? There are other birds around him but he doesn't seem interest playing with them but fly from one perch to other calling his mate so bad. Any ideas in this situation that I can do to help him? I fee bad mydelf lost my lovely bird just because it was accident. Must just happened last nite when everybody asleep or early this morning since the blood on her chest and tummy area still red and some dried out already, sigh I can't think more now, I feel like my love one from family died or something, so heavy inside even just little bird

any advices would be great, thank you so much in advance...
PS: I don't want post her pic when and how she died when hang with string and bloody on her tummy, don't want make people feel sick and sad about her. So I rather just write in words here.
David