Can't take anymore

I' have been  stuck  looping  over a conversation  that' I had with someone recently . The looping over this has been going on for the past 4 days I cant stop and I feel exhausted and suicidal I just can't carry on like this my brain will just not give me a rest. This isn't the first time I've been stuck like this once it went on for a year over a stressful situation. I literally feel like I'm loosing my mind .