Looking for the best way to explain that mom and dad are separate

My daughter (3) expressed some big emotions the other night.

Her dad (26m) and I (25f) are separated, we split before her first birthday. As far as she knows, mommy and daddy are still friends. He came for Christmas last year and we go to the park together at times, not often. Just sometimes. Our schedules don’t align. I have a new partner (24m) who I started to date when she was about a year and a half. She now has a little sister!

Anyways, she spent the day with her dad and after spending the day with her dad (they went to church and a splash pad and had pizza), she told me she misses her Daddy. And I told her it was okay if she misses him, I also miss people when I have to leave them. But then she expressed while she was at church and the splash pad she missed her family. I asked who her family was and she listed off me, my partner, and her little sister. She said that she just had bad feelings when she’s with mommy or daddy because she always misses one of us.

And usually she stays with her dad every other weekend, but him and his fíane broke up which left him homeless and I guess he hasn’t had a job for months, even while he was with his fiancé. So for now I told him he can see her, just not keep overnight until hes stable. (I even had to give him some money when he took her for the day to make sure she’d be fed.) She doesn’t like strangers houses or sleeping in strange places, so while hes couch surfing this is the best we can do. So I know she will miss him more because their typical weekends are shortened.

I’m glad she could recognize her bad feelings. But these are big feelings for my little girl and I want to try to help her cope with them. So I was thinking kid books? I found one called “two homes” and it seems okay. It explains how you have two homes, mommy’s and daddy’s. But I’m unsure if it talks bout the bad feelings that she’s having.

If there’s any better or other way to go about this, I’m open to everything. Even if that means doing more “blended family” activities. I just don’t know where to even begin trying to help her feelings.