there is NO SUCH THING as being too attached.
it is PROVEN that being attached to a caregiver makes kids more secure.
and yes, you wont get any rest because you will be taking care of your baby and your older daughter. this is what parents do! :D
first of all, in order to help your daughter feel security upon your leaving for any reason, YOU must feel confident. you just tell her you will be back, give her the hug and kiss, and snuggle, and go. say you will see her in a little while.
some kids are just more sensitive to this than others, and some times they are more sensitive than other times.
second; it is IMPORTANT that whomever is caring for her when you are leaving NEEDS to distract her. literally pick her up and go find something to do. if they spend less time trying to 'comfort' her the easier it will be to get her over it. they need to get her involved in something else. this is the time when she should be able to do something she doesnt do that often, like play dough, painting, whatever it takes to distract her.
this is also not the time to ignore her either - so at school for instance, they should not try to let her get over it, they should interact with her - and again get her distracted.
theres no reason to keep her from you though. one of the most important think to remember is that kids need connection and attachment! they NEED it. just do your best to comfort your daughter. if you dont have to leave her, dont. she will get through this, and the more you respect her feelings and dont force her to be away from you, the more confidentally she can move forward. fulfilled needs go away, unfulfilled ones turn into undesireable habits. i heard that somewhere too and i never forgot it.
its exhausting. its time consuming. but its parenting. every parent does what they can and what they have to do to help their growing children. again, theres no such thing as 'too attached'. just listen to her emotions. let her know (in more than words) that its ok that she feels this way. if you want her to trust you as she grows, you have to let her trust you now more than ever! :D :D :D
one final word: dont let anyone else tell you what to do. YOU are the parent, YOU are the only person (along with dad) who knows your child inside out. YOU are the only ones who have to make the decisions about how you parent. YOU decide how to deal with something, and you deal with the results of that decision. no one else. so when you feel something is wrong for you - IGNORE IT. this includes magazines, books, online advice, friends, and family. you and dad are the only 2 with the qualifications needed to raise your daughter!
GOOD LUCK! :D :D :D