Ok, you seem to have accepted that he's allowed to say 'no' & DD needs to respect that.
(I love kids, other peoples too! But tickling games & being climbed on I really can't do. I'm not sure why, but I hurt quite easily, shins & joints in particular). I'm ok if they want to sit on me for a cuddle or to watch TV etc, but not if they're tickling & digging elbows knees etc in.
Also I understand about him being frustrated that at 7, she 'needs' you to lay with her in the evenings to go to sleep.
I'm sure plenty of people will be of the opinion he needs to move out and you need to 'put DD first' (and the only way to do it is make him leave) but I disagree.
I wouldn't have asked her what she wants to happen now. It's an adult decision, not a 7 year olds. You need to put what they need first, but this doesn't mean them dictating who does/doesn't live there.
Obviously she's been used to having you to herself and having everything her way. It's not uncommon when you're a single parent, especially with only one child. There often stops being an adult/child relationship and ends up with it being much more 'team us', with them thinking they get equal say in everything.
Did she used to sleep with you?
I'd look at things like starting a good evening routine, where maybe you help her get ready for bed (babying her a bit, by helping her when she can do it by herself) & reading to her for half an hour then she has to read/go to sleep by herself. At first 'reward' her doing this with whatever her currency is.
Start a mummy & DD treat/routine for a non bedtime time. Whether it's a bike ride & hot chocolate on Saturday mornings or playing her favourite game on Tuesday nights. Carve out some time that's just hers. Then some 'family' time... Friday movie nights/walk or bike ride on a Sunday, lunch at the pub. So there's time she looks forward to with DP too, not just competing with him for your attention. Take turns choosing the film/lunch venue/game so it's not DD running the show, it's for all of you.
Talk to DP first.. see what he's up for & if that bedtime routine is something he would be ok with. That'll tell you a lot about him. If he's not up for any of it & has no reasonable alternative - he needs to go.
Best of luck!