Sounds like your in a really confusing place. I haven't been in this position so don't really have any great advice but I your thinking of going back purely out of loneliness/security then its probably not the best choice for your happiness. It's early days and your still finding your feet in this new stage. As for your children I tend to believe they benefit most from happy parents, whether that is parents that are together or not is an individual family thing. If you would like to see if you could rekindle your relationship why not take it back to the beginning. Go on dates, have him pick you up and drop you off. Perhaps it was just him being comfortable and the spark got misplaced. At least you would be able to see if that spark was there rather than going straight back to where you were.
Hope it all works out.