Handling an obsessive ex

Some people just work better as friends than as lovers, and they don't now that until they date. Socially, being on good terms with an ex shows maturity which is seen as a good quality. I feel like this is more of a problem than just a few ppeople on the internet can solve. Perhaps seeking a licensed professional will help.

At the end of the day, you aren't responsible for the happiness of others and people that are unwilling to let go of a relationship that has ended will try to take whatever scraps they can get. It's better to halt conversation with them, block them if necessary, and honestly force them to move on. They will move on if they have no choice to do so. Being friends with an ex is one thing, but if that ex is showing signs that they are unable to accept the decision to end the relationship or are being otherwise disrespectful, then it is completely justified to cut contact. Depending on how obsessed they are, trying to reason with them may make the situation worse. If it has been stated to them before that it is over and they need to move on and yet it persists, then cutting them from your life may be the best thing you can do for everyone involved.

Trust but verify. I think any person would have a legit reason to at least be curious about an ex who still wanted to hang out with the former bf/gf a lot. It depends on the type of relationship but in my mind with monogamy you give your significant other the benefit of the doubt until they give you reason not to.

My ex broke into my house and watched me sleep, It took like 3 years for her to leave me alone, i'm glad it stopped now, I have more stories if anyone's interested.

Not really sure what you mean by you "have a thing with" this girl, are you dating or not? Because if you're not dating then it's not really your business if she's friends with her ex. If you ARE dating, then yes it's your business, and you should talk to her about it. If there's something unsettling about the way she acts around him or the way he behaves you need to let her know. She might not even know it irks you that they still talk all the time or whatever. If she really cares about you, and you tell her it bothers you, then she'll make an effort to keep a distance so that your relationship is safe.

Trust me I've been there and I think the best thing that I would recommend is to avoid your ex all together like don't think about her or him plus blocking would help as well because you need to get rid of anything that will make you think of said ex...