The ex factor

I don’t know what’s weirder; ordering soul food at a Chinese restaurant or getting a surprise call or text from a past lover after so many years of breaking it off. Is it usually completely over once two people that dated break up?
I believe this is debatable. If you had kids from a past relationship it is rather obvious that you will be getting calls and/or text messages from your ex. In fact you should not even wait to get a call from the parent that got custody of the kids, but you should be the one picking up the phone and calling to find out how your kids are doing. So what if on the other hand, no kids were involved in the relationship and you have moved on to another relationship? Is a call or text from the ex legitimate? Would your spouse be overreacting if s/he found out that you have been speaking with an ex and got jealous?
There should have been a reason the two of you broke up in the first place; whether you caught them cheating on you or you were just not compatible, or the relationship was abusive and decided to call it quits. One thing would lead to another if for any reason a past relationship would be rekindled. On the other hand what caliber of inhumanity would it be if you met an ex that was in need and indeed denied to help? Are there rules to follow as far as exes are concerned?
Your conscious is always crystal clear unless if you are a downright murderer. If you do it and your conscious says no, then you know it’s wrong. It would be unacceptable if you start flirting with an ex knowing that you are in another relationship. If anything it is dangerous; it’s like a land mine waiting to be stepped on and explode.