I have a different thread going, as I think mine's NW problem is OT from dropping the nap (just started afternoon nursery) BUT I wanted to chime in with some extra mama love because I'm equally sleep-deprived and it just sucks. I'm a mild insomniac from time to time, so when mine wakes, if it's after 2am, I'm up for the day, can't go back to sleep. So I really want a solution too!
A few thoughts on your situation:
1 - Have you tried a GRO clock or similar? It worked wonders for my daughter when we first got it. Over the holidays we were traveling and without it and I think my daughter has forgotten it's role, so I'm having to reintroduce it and remind her of what it means, but she does understand it, and it does help.
2. My DD does not want to be alone right now either and will think of any excuse to make me stay longer. And she gets me all day long, so it's not a needing mommy time thing. I think it's a toddler, I don't want to be alone thing. What I've been using the past few days that seems to help a little bit is checking on her after 1 minute, 5 minutes, 10 minutes. By the 10 minute mark she's usually back asleep without having seen me in a while. I'm hoping if I stay consistent with this, it will reinforce that she is safe, and I am around, and she doesn't need me to come in to fall asleep. I don't know yet whether it will help with the NW, but thought I'd share.
3. I am very clear about the things I'm saying to DD before she goes to bed. Always the same thing: Time for bed. I love you. I will check on you in 1 minute. And I will see you in the morning when it's wake-up time and the sun is on your clock. You need to stay in bed until the sun is up and then you can call for me. Not before then. I love you, and I'll check on you in 1 minute." And then in the repeated visits, "I'm so proud of you for staying in your bed. The star are up and it's sleepy time. I love you and I'll check on you in 5 minutes." Occasionally I get to the 10 minute check, but rarely. I'm hoping the consistent message of it's sleepy time, stay in your bed until the sun comes up will eventually sink in. And then in the morning, on the rare occasion she didn't call for me in the night I make a really big deal of it, and say how proud of her I am. If she did call for me, I say that I'm so tired because she woke me up, and tonight you can sleep all night without calling for me, etc.
4. For the weeks your DH is away, could you co-sleep? Maybe you don't want to go there, but I find when we co-sleep during traveling, and we get back home, it only takes a few nights for DD to go back to sleeping on her own again. And by that time your husband would be back. This might let you get some sleep when you most need it?
I hope something in here is helpful to you!
Stay strong, it can't last forever, can it?! ;-)