What would you do?! I need some non biased opinions

I broke up with bd 6 months ago and went into another relationship (yes stupid I know) well I thought I was in love and now I’m not so sure. I’ve been having dreams non stop of my ex and wanting to get back with him. I know it’s probably not a good idea because of what we’ve been through and the fact that I went into another relationship but I feel like I made a big mistake. My ex is the father of my 3 youngest kids but problem is that he’s irresponsible and doesn’t help me with anything child related...the new guy is alright but I feel like the spark is gone for some reason...my question is what would you do? Stay and see if things get better? Go with Ex? Or stay alone for a while