I'm going to bail on a vacation because my friend is an insecure alcoholic
That is a shame to hear. Are you sure they're an alcoholic?
Yes, she keeps asking me to check up on her all the time.
It's wrong to bail on plans and abandon friends. Especially when they need you for help.
S/he's not worth the effort.
It is not good to leave someone that is supposed to be a friend. People will think you are not trustworthy and no one will want to hang out with you.