My ex is in the picture again.

So my ex came back and well he and I are talking but I feel weird because he's taken and so am I but I told him I'm single he said good but I love and like him a lot and I also feel like I shouldn't be talking to him I told my current boyfriend I'm talking to my ex but I only say little things I haven't let him check my phone or anything I'm afraid because I feel my ex is flirting with me to be honest and I want to see him and he really wants to see me like this could go on forever I could rant about everything get me like he stopped messaging me and we stopped talking about three months ago I changed my number and all he tried contacting the other number and well found out it was disconnected and then he messaged me on Instagram so then we message each other on Instagram and well hell randomly ask to call me it's barely been two days that we have been talking what do you think?