Ex-ish? Help!

I dated this guy for a month and it was awesome, then we sort of idk kind of broke it off, don't ask me how I'm not sure. It's been about a week and he just texted saying he missed me and I missed him too and the thing is we worked so well together! I thought I could have had a long term relationship with him. My BFF says I should ignore him but I fell head over heels for him and I'm wanting to give us a second chance...