My baby won't sleep anymore

She takes 30 min cat naps throughout the day and wakes up at 3 am every morning and won't go back to sleep. I get so sleep deprived and exhausted I have suicidal thoughts at night when I'm up with her. I can't take it anymore I just feel so empty and broken and me and her father fight all night because we're so tired and stressed and it just makes it worse. :( she used to sleep until 6. Just this week she's started waking up at like 3 and then refusing to fall back asleep. unless I put her in the rock n play then she'll fall back asleep. But only for an hour or two.