Framing feedback as an opportunity to improve and better yourself/your company, be it toning down something bad or ramping up something good, as opposed to a method for self-validation could help.
You could also look at it from two perspectives. From one perspective, feedback promotes improvement for the good of the company. In this light, negative feedback could be demotivating. The other perspective, preventing your company from declining in quality or regressing, could improve your motivation in the face of negative feedback and perhaps even prevent you from getting complacent with ample amounts of positive feedback.
Since you mentioned meditation, one way to improve at handling negative and positive feedback is to be mindful about it by accepting the feedback for what it is and also accepting your feelings towards it. In fact, meditation can help towards this. This can allow you to take a step back and analyse where to go from here as opposed to extremes of emotion clouding your judgement.
I think it still stings, especially if you invest a lot of yourself into your product. Like anything, it is a skill and it does improve with practice, especially deliberate practice.
But, then, Ford supposedly said that if he listened to customer feedback, he would have been trying to build a faster horse. So, I will suggest a high percentage of people will not have good feedback for you, period. Even most people with the problem won't understand the problem space well enough to give good feedback. This is part of why metrics are so popular. Over time, I have become less focused on what people say and more focused on moving certain numbers. Is it getting me traffic? Is it improving the bottom line? Etc.
Most negative feedback is equally emotionally driven and uninformative. If people react very negatively, it can be useful to know that you are doing something seriously wrong, but it probably won't tell you what you are doing wrong.
A couple of things are really useful and you won't see them often:
Statements quantifying relative or subjective value, i.e. "This works better/worse for me than (other thing)."
Statements quantifying absolute or objective value, i.e. "I need a thing that goes X speed and yours is the only one that does that" or "I need a thing that goes X speed and yours does not do that so it has no value for me." Or even "You have a typo/grammatical error/etc"
When I paid insurance claims, we were taught to evaluate red flags and refer things to the fraud department if there were enough suspicious indicators. A lot of that has to do with context and patterns of behavior. I already focused a lot on patterns of behavior, but working there firmed up some of my understanding of how to do that well. Some people will talk trash about you but use your product anyway. Others will say glowing things and not give you a dime. Actions always speak louder than words. Don't let their words distract you overly much.
There are extremes in everything and also some people give strong negative feedback because they want to see an improvement, some give good feedback because they don't want to make you feel bad. You need to think about it, put in perspective to what you think and try to extract only the relevant information.
Seriously, just try to look at the opinions critically, and even more so at your reaction to them. If you see yourself too involved, stop and think, why are you so winded-up about something someone said.
It boils down to keeping your identity small (http://www.paulgraham.com/identity.html), which may or may not be truly possible in practice for humans who do not lead a monastic life.
Any feedback that is content-free ( purely positive or negative ) gives you no inspiration for an opportunity to create an improvement.
Any feedback that possess content ( regardless of its polarity ) gives you inspiration for an opportunity to create an improvement.
You control your reaction. If you choose to be open to being inspired by the possibility of an opportunity for creating an improvement, then you can also choose to meet that opportunity, reflect, and create an improvement that may work for you.
Feedback from someone other than you is not a necessary condition for this type of improvement, tho it can contribute, and it is often available and being offered to you.
If you choose to focus on the polarity of the feedback ( and get carried away with how "good" or how "bad" you interpret it as ), you may get in the way of focussing on the content.
Another way to think of it is that there are some very smart experts, who know exactly the kinds of things that could go wrong with whatever you are trying to achieve, and so there feedback can contain lots of relevant content, and it may just so happen that they, for whatever reasons owing to their own personalities, mostly express themselves from an adversarial point of view, and season their content with a lot of negative polarity.
Maybe that is kind of like Indiana Jones, in how the secret treasure always lies at the end of a cave of boobytraps and dangers. All those things are distractions, and if you navigate them correctly, you can slip past them, and get the treasure, and make it out with your head ( and hat ). If you lose your head, owing to the distractions, then that's your choice.
You can see separating the polarity of the feedback from its content as an opportunity to choose to either focus on what you are achieving and ignore and slip past distractions, or to focus on ego games and pretending others are wrong and you are right. Neither of these is right or wrong, tho one may work for what you want to achieve more than the other.
If your goal is what you are trying to achieve and that is what the feedback is about, the more you focus on content, and the less you focus on polarity, the more you are focussing on things that work to contribute to that achievement.
If you feel this may not be easy, then you can choose to see __that__ as an opportunity to create an improvement in focus.
I more or less ignore positive feedback, other than to thank the reviewer.