I can only imagine what a difficult time you are going though. My daughter was 1 when she was having issues with not gaining, and then loosing weight, with all the needle pricks she still 1 ½ years latter does not want anyone in scrubs to touch her, and she never even went to the hospital. My son had minor outpatient surgery and went into a deep depression for about a week following. So I can understand where your concern for her mental well being is at this time. These are a few of my thoughts; maybe one will work for you. Dates – you do not HAVE to go out if you feel too guilty. See if you can get a sitter to take your older daughter out to a movie or something, and set up a portable DVD player in your younger daughter’s room and have a quiet dinner and movie on the couch with your hubby. Not that I would advocate the DVD thing on a regular basis, but once in a while to grab a break will not hurt. Have the same sitter come over once a week to take care of the girls while you and your husband get the yard work done together, clean the garage, etc. It may not be a date, but it is time together and would give you daughter time to get use to someone new with you still being there if she needs you. In a month or so she may be ready for you to leave her. Also remember, if you decide to just leave here with a sitter and go, she may cry for a while, but she will be perfectly fine – as another mom, I know it will be harder on you than her.
For re-establishing trust of other people, have you tried any group activities with her? I did WeJoySing with my little one, it gave her a chance to be around a “teacher” other kids her age and still have me right by her. I am not sure exactly what the illness is she has, but if she is allowed to be out and about with others, this may help with the anxiety of being around other people. They also have an early intervention program that I think is more for kids with autism and speech delays, etc. but it may be worth asking about to see if it can help you and your daughter. Good luck