Hi D.,
Got a bed big enough for the 3 of you? Take turns as to the side of the bed you will lay down on to make both babies feel they are getting fair treatment: "Tonight I'll be closest to Hannah and tommorow night I'll lay beside you Micah."
Basically, you lay there till they fall asleep and then slide gently off the bed so as not to re-awaken.
Wind them down with telling stories or praying with them. Consider this as 'quality' time with them. Ask them a simple question like: "What was the happiest part of your day today?"
Sometimes things that have been bothering them get shared in this atmosphere.
[When we were talking about having just moved from our old house, my youngest burst out crying, out of the blue. Turns out unbeknownst to us he was so angry that we'd painted the walls of their room white(to sell the house) and nobody had cared that he 'loved those walls' - each of which had been painted a different primary color. His little storm passed though after his big brother and I commiserated with him - he had been comforted.]
It may take long at first for them to fall asleep quickly - routines take a little time to establish.
But your closeness will have a calming, relaxing effect on them. They'll fall asleep feeling safe and secure. It's a very gently way of dealing with this issue. It will serve to calm and relax you, also.
I did this when my boys were little (2 years apart), up to the ages of about 5 and 7. One is now 18 years old and the other is 20 years old. Neither are 'mama's boys'. The 20 year old is married and he and his wife graduate from college (UT-Dallas) Dec. of this year. And the 18 year old goes away to college this coming fall.
I have so many good memories of this time. I felt so close to them. Cuddling and basking in their wonderful child softness and the smell of their hair and skin.
"But won't this make them dependent on me always having to do this in order for them to get to sleep?"
Yes. But they will grow out of it eventually. Mine did. My husband and I would often take turns with this, so that helped too. After a particularly busy day, this may be the only 'quality time', 'one on one time' you get to have with your kids.
"But yours were 2 boys, mine are a son and a daughter." No big whoop. At this age their sleeping together is a non-issue.
Don't worry sweet mother. Look at this as just another opportunity to enjoy your children. It goes by so fast. I have so many good memories of this time and find myself very often yearning for that sleepy-time togetherness we shared so many years ago.
(A really great book that you may find helpful: Nightime Parenting.) And a wonderful support group called La Leche League is also a wonderful resource. It meets primarily for breast-feeding issues, but any and everything related to younger child rearing gets covered also.
This may not work for you, but I think it's worth a try.
Hang in there!