You poor thing
I promise you this feeling will pass.
She does love you, you are her mum and noone will ever compare quite to that. Often my DD plays up more with me purely because she knows she can, and goes to other people rather than me as they are more interesting and "unplayed with".
I think a lot of mums find this, dad is the "novelty" at certain phases.
There was a little girl I used to nanny for, and she was SUCH a daddys girl from 2-3 years old, if mum got home before dad she would scream go away I want dad, if mum put her to bed she would kick up a HUGE fuss, if they went out she would cry asking for dad to come too etc. Then at about 3 she suddenly stopped, and would be telling me about mum doing her hair, asking if we could paint her a picture, saying "mummy does this" "I love mummy when's she home" etc.
It was SO tough on her mum for the year or so, and it wasn't really apparent why, but it didn't last.
One thing I did used to think was maybe it was because mum would always take the tantrums and still be there, and she had the security of knowing she would always come back, whereas dad was more of a "challenge" to get time and attention from. He was a lovely dad, but he wasn't available quite as much time wise, and would leave her to it if she started tantrum-ing.
Don't give in to ANY suicidal thoughts. It will honestly get better, I've been there and now I look back it all seems so unimportant in the scale of things, but at the time it felt like I was in a hopeless black hole with nothing to look forward to. But it couldn't have been further from the truth. Plan a break away for just you and DH/a spa day for you to relax. You need to break out of day to day life for a bit to help the cycle of emotions.
This is a natural state of her finding her boundaries and building relationships. She knows she can push you away and you will still be there, and she probably likes the attention of you trying after she says no. This is a good thing, it will make her feel secure and loved. Don't take it personally, all children go through phases, in a few months-a year it will most likely reverse.
Sorry for waffling, and I hope none of that's made you feel worse or come across wrong. xxx