So what would have happened if your colleague would have sent a news item saying that the drug saved a girl from suicidal thoughts? All you are responsible for is doing what marketing told you. And even marketing isn’t evil enough to label it all bad. Now if you were the guy that tested the drug and released on the market, that would be a different story.
So thank you for sharing a personal experience, but I don’t feel it fits the message you wanted to send. Even weapon manufacturers could feel conflicted. Imagine that you designed a gun and then the gun got stuck when it was supposed to save a girl’s life. Or it worked perfectly in the hands of a killer. Engineers are supposed to feel guilty if their work doesn’t work as intended, not to consider all the implications of its use. You feel guilty for writing a marketing site? Phaw! I hope that’s your worst life experience.