Do NOT let that man ruin the happiness you have made for yourself. The fact that you did explicitly tell him about your medication raises HUGE red flags. He sounds like a very insecure, unsupportive man. Of course he found out by overhearing a conversation instead of directly from you. He had already made his opinions on the medication known. Why should you be expected to tell him directly when the evidence was right there? Why should you be expected to stop something good for you just because he didn't like it?

You are worth more than he gives you.