How to cope with lack of sleep, & a constant crying baby😢

My daughter is nearly 7 months old & I now find myself really struggling, up until 6 months she was a brilliant baby apart from the sleeping but it was bearable, now the past month she has now become a nightmare especially at bedtime! She won't sleep in her crib (transitioned to crib from Moses basket last month) so that never helped things, but she also won't sleep with me in my bed now either😕 and she has gone off her milk so won't drink a bottle either! She just won't settle she's crying all night.. I am absolutely exhausted to the point I now find myself sitting there at night in bed crying. My partner works shifts and when he is home he doesn't help me what's so ever; I just don't know how to get past being sleep deprived and what to do, If anyone has been through the same how do I get past it😞 feel like a bad mother, & feel so down. Thanks for reading