He cannot bear to see the udhiyah when it is being slaughtered

Praise
be to Allah

It is best for the individual to slaughter his own
udhiyah himself. If he cannot do that or does not want to do it, there
is nothing wrong with appointing someone else to do it and watching it
being slaughtered. If he cannot do that or does not want to do it, then
there is nothing wrong with him being absent at the time when it is
slaughtered. 

Appointing someone else to slaughter the udhiyah is
permissible, and there is no difference of opinion among the scholars
concerning that. Attending the slaughter is mustahabb (encouraged) but is
not obligatory. 

Ibn Qudaamah (may Allah have mercy on him) said: 

If he slaughters it with his own hand, that is preferable,
because the Prophet (blessings and peace of Allah be upon him) sacrificed
two horned rams that were white speckled with black. He slaughtered them
with his own hand, said Bismillaah and Allaahu akbar, and put
his foot on their necks; and he slaughtered some of the sacrificial camels
that he brought for his Hajj, sixty-three camels, with his own hand. 

But if he appoints someone else to do it on his behalf, that
is permissible, because the Prophet (blessings and peace of Allah be upon
him) appointed someone else to slaughter the remaining sacrificial camels
after he had slaughtered sixty-three of them. There is no difference of
scholarly opinion concerning this, but it is mustahabb to be present when
they are slaughtered.

End quote from al-Mughni (13/389-390) 

It says in Fataawa al-Lajnah ad-Daa’imah (10/441): The
reward for the udhiyah, if it is voluntary, will be shared by everyone who
is included in the intention, even if he is not present. Because the Prophet
(blessings and peace of Allah be upon him) said: “Deeds are but by
intentions, and each person will have but that which he intended.” End
quote. 

For more information, please see the answer to question no.
175475. 

And Allah knows best.