Oh my goodness, it sounds like you just wrote my biography. I have co-slept w/ just dd for 3 years now. Hubby moved out voluntarily. Now I have a DS 6 mos, and I sleep with DD and DS and hubby is still in his own bed. I know where you're coming from about the relationship with hubby. The problem is I love sleeping with my babies -- and sleeping with my snoring husband, well, I would have to get use to it again I suppose, after alll, the kids will move out someday (maybe). We just bought another king-size bed so that he wouldn't have to sleep in the little full-size bed (he's a big man). So, enough about me.
The first thing you must decide is if you realllllyyyy want her out of your bed, or do you truly enjoy sleeping with her. Next I would make her a pretty room with as much new things as you can afford, bedroom furniture, curtains, covers, sheets, etc. etc. Then a suggestion that I may use if and when the time comes is from Elizabeth Pantley's book, "The No Cry Sleep Solution." She recommends making a book for any toddler going thru a change. You can cut pictures out of catalogs, of big girls sleeping in their own room, and mommy and daddy sleeping in their own room, or draw your own and make a book for her. Read the book over and over and she will start getting the picture in her head of sleeping alone.
She also suggests keeping a mattress or comfortable place for her to sleep on your bedroom floor, in case she needs to come there in the mid of the night, with clear instructions that she is not to disturb mom and dad, but to lay quietly on the space just for her.
Another thing I read was to give your children some "get out of bed free" passes -- just for drink, bathroom, or one last hug. Once the passes are used up no more getting out of bed.
And one more thing was if she sleeps all night in her own bed for 6 days, then she gets to "camp out" with mom and dad on the 7th day (that might work when she's a little older).
As far as getting her to sleep???? That may be tougher. Do you have a set routine with her now? Let me tell ya that she may get highly upset if you disrupt that routine when baby gets here. So, try and make a routine that you think will work for you when baby gets here -- and ask for daddy's help as much as possible. There were nights DD fell asleep in front of the tv as I was trying to get DS to sleep -- something I swore I would never do.
Anyways I hope I didn't give you way too much info. Best wishes for you and I would love to know if you decide to use these suggestions and if they work for you.