Hey Rachel..
Sorry you're having such a hard time. Big {{{{HUGS}}}}}}} coming your way.
Sleep training isn't going to work unless both you and your husband are on the same page. I'm sure you know this! So sit down and chat with him seriously (not in the middle of the night when you're both exhausted!). Make a plan - even write it down! Then, do not deviate from said plan. Unless, of course, he enjoys waking up repeatedly and then sleeping with Saree. In which case, I would leave LO with DH for the night and wear earplugs... OK, a little extreme, but you know what i mean, right?
I find that I have to psych myself up all day if I know I'm going to be doing something hard during the night (like pu/pd). If I don't mentally prepare myself, I can't do it! Remind yourself that you're going to fix it tonight (and maybe tomorrow night, and the night after), and that you're not going to get a lot of sleep, but in the end it will be worth. And it soooooo is worth it. After Christmas holidays, Abby's night sleep was totally wrecked. So after one day of recovery, I went back and did PU/PD for 2 hours. Only had to do it for one night. And now, we put her to bed at 8pm awake, she sleeps 'til around 1:30am, I feed her then back to bed, and she's awake on and off from 5:30-7:30 but usually I can just leave her and she'll go back to sleep. Occasionally I will have to sooth her once or twice during the night, but it's really easy to do. AND she's hit major milestones these last two weeks - a tooth and she rolls over and scoots around in the crib a ton! And I think we're approaching a time where I can cut her one night feed out. And honestly, i think that when I do that, I can expect her to stop most night wakes.
Since both our LOs have changed a ton since this post has started, maybe you should consider starting a new topic so that we can all look at it with fresh eyes. Also post her current routine and night wakes. We'll brainstorm and see what we can come up with. This too shall pass!!! You'll get through this.