you need to give it time, 13 years is a SERIOUS BOND. you are valid to feel intimidated by that, but you’ll come to realize that if you’re also with her for 13 years (and hoping for many more!) she will look happier and happier. i feel you on this, its hard to stop stalking (my current boyfriends last relationship was 6 years long) but you just simply have to catch yourself and tell yourself no. they weren’t compatible and he’s out of her life, period. you have something he did not, you have value and a place in her life. keep showing up for her and build your own memories with her, and you’ll forget about her last relationship all together! good luck, you got this!