Firt off, remind yourself to not take it personally. It's a phase. There's a good chance that she sees it affecting you, and that's enough reinforcement. Not that she's malicous or anything, but it's attention to a behavior.
Second, make a time-out spot that is not their room. Preferably a place where they can see the activity but not participate (and that you can see them). Have a timer. 3 minutes for the 3-year-old, 5 minutes for the 5-year-old. They get one warning when they misbehave (get mouthy) and then it's time out. If they get up before time out is over, you start the time over (make sure they see you). The time doesn't start until they are calm (I had to 'train' my kids to sit in time out no matter how much screaming first before I could insitute this rule). If you need to, physically take them to time out (at the first NO about it) and be prepared to sit and hold them in time out for the full time. Yep, you're going to be exhausted some days. Make sure your husband is doing the same thing or they'll play you off each other. And schedule some girl time, where he takes the kids, and some date-time where a babysitter takes them, so you can get away for a while. There is nothing wrong with needing a break!
The key to this is being 100% consistant. When you tell them to do something, expect it to be done or enforce a consequence (I take away tv or video games, but my kids are a bit older now; pick something they really like and give them 2 warnings for now, whittle it down to just one). Don't threaten anything you're not willing to follow through on! If the kids misbehave when you're out, give them a time out there. Just take them to a corner away from whatevers going on, and have them sit for the 3 or 5 minutes. I had to do this recently at a family birthday party, took him out of the party room and I had so many 'solicitous' people trying to cheer him up. I just had to calmly tell them "he can't talk to anyone right now, he's in time out." And sometimes you just have to pick up and leave right then and there. When they see you're serious and are really going to follow through, they'll start to cooperate more.
Oh, and give lots of praise and hugs when they do something the first time! What you give attention to will increase!
Hang in there! The cuddles and hugs and sweet kids will come back!