I did something similar too(but it was a friend with an asthma attack) and they reacted pretty much the same way your friend. So don’t beat yourself up, they probably didn’t mind it, especially because you offered help and showed you cared instead of just walking away. Maybe to not have that kinda guilt feeling, you could ask them if it happens again, what you could do to help beforehand. As someone who went through something similar I hope this helps :)