If I go to bed, unsure if I will decide to allow myself to fall asleep or just rest until my husband comes home, should I say hamapil?
Essentially, we say hamapil when we are going to sleep for the night. If you still have not decided if you are going to go to sleep, why not wait until you have decided? If you are afraid that you will fall asleep while “deciding” if you should go to sleep or not, and you are not going to wake up when your husband comes home, then you can say hamapil earlier. However, if you will wake up when your husband comes home, wait until later to say it.
Keren L’dovid O:CH 60, Eshel Avrohom Butchatch O:CH 139.