H.G.
Sorry to hear that it didn't work out for you guys. My daughter just turned 4 when her dad and I split and she reacted much the same. I've reassured her that I'll never leave her no matter what. Also let her know that daddy's always there for her even if he doesn't live there anymore. She'll take it hard but the more positive spin you put on it will determine how long she'll act out and blow him off.
When you put her on time out tell her it's because you love her and don't want her to act that way. When you let her up, reassure her again that you love her - the other advice you've had is really good! You might want to try counseling - I did with my kids and it really helps the parent and the child(ren).
Call me if you find yourself in need of an ear to listen - sometimes it helps too, if she has "friends" who've been through it. My daughter thought it was the worst thing in the world til she found out how many other kids have dads who don't live with them. Talk to ya soon - hang in there!!