Focus on who is in her life, the people who do love her and chose to spend time with her.
At 3 you should be able to distract her and any direct response should be clear, to the point, unemotional.
So "your dad is busy, I will tell you if he calls" (I never referred to DD's 'father' as "Daddy" because that wasn't what he was to her)
It's hard to explain and its a fine line to tread. But don't lie to her, be kind with the truths, keep it age appropriate, keep replies short and to the point.
A fun game was to name all our family and friends (obvs not the father) and if she wanted to we would draw them all. I have a fab picture of our entire family and pets (even the goldfish!) - in stick from, surrounded by flowers and stood on a rainbow. We aren't a small family, it was A3 size! Took her ages and she had it on her wall for a few years. It's in her memory box now.
You need her to trust that you are the one with the answers, so she feels comfortable coming to you in the years ahead. Don't slag him off (at least not in front of her). Never talk him down. Stay even and unemotional where he is concerned.
She will get upset, in years to come.
There will be more answers.
My DD is 13 and her "father" bastardshithead has never been near, no contact at all. I tried for years but have left him to rot in his own bile now. DD is in an angry phase, but again I tell her "it's not about who isn't in your life, it's about the people who are and the people who love you without question"