When you say you have been separated for a year and a half, I'm going to assume you actually got divorced somewhere in there, otherwise you wouldn't be engaged.There's a reason that makes a difference: If you are still working with a temporary custody agreement, and working through a settlement, it makes sense that you might need a little more contact. If you have a final decree, and a set schedule for visitation, your ex should not need to contact you more than a couple times a week. Of course, if your kids want to talk to you every night before bed, that's a separate thing.The way to handle it is to keep the communication businesslike. Don't respond to texts unless there is a particular, urgent question regarding the welfare of the children. And don't answer the phone unless you are expecting your children to call. Let her leave a message and if its urgent you call back.As to emails, the same applies. Only respond when necessary, and keep your replies businesslike and only about the children.Your fiancee doesn't have kids, so it's going to be harder for her to understand that you have a co-parent in your life, for the rest of your life. If your ex is being chatty, that's a problem, but if it's just routine info about the kids, and she's in the habit of sending a quick text to update you (so she doesn't forget) then your fiancee doesn't really have much to complain about.