Your first launch isn't meant to make you a millionaire.
As a beginner in any field and especially in the information industry, don't expect a great reward for your efforts from the first time, instead focus on the feedback that will make you better by time.
As a human being, you will get frustrated when you get rejected, especially when it comes from your target audience. But remember that this won't last for so long, and don't even consider it as a loss. Instead, consider it as a chain of steps to reach your goal.
At the end, we all want to reach to the well-oiled machine (marketing funnel process), where you pay money on marketing from one side and get positive ROI from the other side.
No matter how much time or effort you put into your start-up, you'll always have people who'll criticize your work in one way or another. The key here is consistency and persistence. Don't allow your fear, to stop you from what you're doing. Whether you're starting up or want to scale up, don't let small things destroy the big image.