The question "is heartbreak the way humans experience it right now a good thing" is one of the more complex questions about the human condition,yes. My mental modell of all that is kinda like the following: On an neurochemical level, the way "love" stimulates the reward-centers has been likened to "cocaine".Its an extremely strong conditioning, addiction even. So of course your brain wants to satisfy that condition by all means possible. If we have a look at popular culture, its kinda expected to have extreme reactions to heartbreak: people fall into depression, start rationalizing all kinds of really crazy behaviour (stalking, death threats, lifechanging roadtrips) etc etc. To avoid all that you have to thoroughly impress on your emotional side that its over: thats why some people do the whole "burn everything that connects me with her", others just overwrite that old emotion with new (irrational)emotions like anger, hold a symbolic funeral, repeat it to youself everyday in a mirror etc. Unfortunately I am not aware of studies about optimal treatment of heartbreak, but common wisdom is: NO contact at all in the beginning, allow yourself to grieve, find solace with friends/familiy, and somehow redefine your sense of selfesteem- take up painting/coding/comething you have always wanted to do. If one wanted to go the rational route: research neurochemistry, find out wether its really like cocaine-addiction, do whatever helps with cocaine-withdrawal. (or the other most closely related drug-withdrawal).

You can write down your own goals to make them clearer to you. If you are clear about what you want to do it's harder for someone else to give you other goals then when you are empty. There are various kind of things you can do to learn emotional control. I remember times in the past where strong emotions could cloud my mind but after doing a lot of meditation that's not true for me anymore. In the absence of ugh-fields or a lot of unknowns strong emotions make me think clearly and I can still follow rules based heuristics. The most charged emotional situation I can think of that likely would have freaked a lot of people out was when it was past midnight and I was walking alone and a guy grabbed me and told me: "Give me 5 Euros or I'll kill you" To get to something more speculative, I have the idea that love is a lot of conditioning. If everytime you think about X, you feel good, the next time you think about X you will feel even more good. A bit unpredictability thrown in generally increases the effect. If you repeat that a thousand times you get a pretty strong stimulus. Almost wireheading ;) Of course there are additional effects that comes with physical intimacy. Speaking about them would be even more speculative.