Should i go back?

I walked out on my husband over 5 months ago, taking our now 15 month old son with me. It was one of the hardest things i have ever had to do as i loved him and cared for him but we were not getting along, mainly due to money worries and lack of communication. I stupidly started dating just over a month after we split whilst i was still grieving the break up of my marriage causing arguements between my ex and me, i know this hurt him a lot. Although i was secretly hurting too but didn't have the courage to admit this, even to myself.

After 4 months of dating this other guy, he dumps me! right out of the blue, reason being that he felt i was holding onto my ex. which in truth i was. Although i knew the spark had gone out of my marriage, i still had pangs of hurt when i thought of happy times we had as a family or heard certain songs!! Although i had also fallen for the other guy by now, so now my head and heart are confused!!!

My husband and I are now spending time together as friends, taking our son out and enjoying each other's company. There is a lot of love and companionship between us and although he's made it clear he wants to start afresh, I'm scared it wont work as the spark and passion has gone.

I have decided to stay as friends for the time being, get over the other guy and see what progresses with my ex, although i can't help but wonder is it possible to get the spark back? Can you have passionate love as well as deep companionship? and if we spend more time together communicating do you think it would be worth one more try?