Hi Jasmine,
I don't have any book recommendations but I wanted to offer just one bit of advice. My parents divorced when I was 11. It was very amicable and thankfully they have remained friends all these years. The best advice I can give to parents who are divorcing: don't ever speak ill of your ex-spouse to your children. That is their parent, they love you both. To this day, years and years after their divorce, I've never heard either one of my parents say a bad thing about the other. It was the greatest gift they ever given me.
Now, if I may chime in about your boyfriend and being called 'daddy'. I think it is important for divorced parents to keep their boyfriend/girlfriends separate from their kids (don't introduce them) until they know that this is someone who will be around for a long time. If the kids have already met the BF, I'd try to keep strong boundaries about family time and social time. Allow the kids to adjust as much as possible to their new family dynamic before introducing a new person. So, all that being said, I don't think a BF should be called 'daddy' until it is clear that this person will be a daddy in their life, for their life (ie marriage/committment). Personally, I think it creates confusion emotionally for the children to call another person 'daddy/mommy'. I'm no expert, it's all just my opinion. And who am I to say what is right or wrong? Just my thoughts :)
Bests!