Valves (you have two in your penis, if I remember correctly) are like one-way doors that blood can go through. In your penis’s normal resting state, the valves are half-open, resulting in having a flaccid penis that is not completely shriveled up (blood has to keep on circulating through your penis to keep it alive). When you get an erection, the valves open fully and blood rushes into your penis. Once the penis has become engorged with blood, the valves close thus letting no more blood into the penis, and having the added effect of keeping the blood that’s already in the penis from escaping.
Taking our door analogy from earlier, therefore think of valve damage as breaking the hinges on the doors (in other words, you’re trying to force the one-way door to open the other way as well). So, valve damage is characterised by one of two possible problems. Either your valves stay somewhat closed and you cannot get an erection because blood cannot get into your penis fast enough, or your valves stay open, resulting in you being able to get an erection, but not being able to keep it for very long at all.
Regarding healing, do what the rest of us do when we mess things up: take a complete break from PE, and possibly even other forms of penis ‘exercise’ - referring here to sex and/or masturbation. However, if you’d rather engage in those latter two things, then maybe wearing a cock ring might help you.
Hope this helps. :)