Have to agree with your husband on this. Had he been in your daughter's room from the day he came home it would be different, it would be a bigger adjustment for her now, hearing him fuss and cry and being disturbed. Is there a place other than your's and your daughter's room to put his crib? A hallway or closet will work if there's no other room.
Learn to let him self-soothe, no need to always pick him up, you can change his diaper without picking him up, too. Sometimes all babies need is to have their back or leg patted or their face gently stroked to relax them back to sleep, or to be left alone to figure it out, they can actually learn this much earlier in life. Leave the light off when you go to him, speak in a soft whisper, don't pick him up, try to soothe him and reassure him, then leave before he is asleep. Limit engaging with him so he senses it's time to sleep, the more attention you give him the more he will need. Also, have your husband go to him when he wakes since he can't nurse off Dad, and have him soothe him so he can go back to sleep.
Work on him sleeping through the night along with the weaning, you should be able to go to just one feeding through the night now, nurse him right before he goes to bed. When you have that feeding eliminated work on no more others through the night, just at bedtime and in the morning and you can hopefully get a full night of rest. Breastmilk is still the most important nutrition for him right now, until he's a year, so nurse him a little, offer the solids, and you'll see that as he eats more solids he will need to nurse less.
Once he's sleeping through the night you can put him in with big sister : )