Okay, this is what I always say about exes and I think many people on here will agree that it isn't okay to continueously be in contact with your ex because trust issues start to manifest. I know that in the past that I've had trust issues when it comes to exes because I've actually had a girl cheat on me before with an ex while they were still in contact. I don't think it's okay especially if you're not comfortable with it.
I will do my best to reply with an educated, humble and honest answer. Ultimately, it is up to you whether you want to listen to my advice or ignore it completely. Sometimes, my advice may be wrong; occasionally, it will be right. Regardless, I want to do my best to give people answers they are seeking.