Moving on

JA
Hi everyone, this is the first time I've posted. I've recently moved out of the home I shared with my bf of 13/14years. We went on a break a year past sept then decided to split a year past December. However while I was waiting to be housed I remained at the home with him, we were still on okay terms and things were okay most of the time. I moved out in January this year. The first problem is that since moving out he's taken it pretty bad and admitted he didn't think I would really leave. The second problem is that he never told his friends/family until I moved out that we were over and don't think he's actually told them the time period we were split for. So in the meantime I've been in touch with someone from our past, a mutual friend but who also works at the same company, and often the same site as my ex. I think we both always had feelings for the other but never acted on them, or even really admitted to ourselves that it was real feelings. My dilemma is how do I tell my ex this? He was insecure about this man years ago and has mentioned him a couple of times in recent conversations. I'm worried something will happen at their place of work, I'm worried that everyone (excluding my family and close friends who knew we were split) will think I've left my ex for this guy or even that I cheated with him. I know this shouldn't matter but we were together so long all our friends are mutual friends (he's friends with all my girlfriends partners and vice versa). My feelings for this guy have developed and I feel like I might end up hurting him by tiptoeing around my ex. On more than one occasion one of us has had a bit of a freak out about what we are doing and have feelings of guilt etc. What would you advise? I know that there's an unwritten rule that you don't date your exes friends and I never imagined myself to do something like this, as cliche as it sounds my feelings are too strong to ignore and he makes me happy.