[28M] has feelings for [27F], but she's currently in a relationship with [45M]. Should I tell her how I feel?

I've been friends with this girl for nearly a decade. We share similar thoughts, provide each other with support, and always look out for one another. Although we've kept in touch sporadically over the years, I've recently moved close enough for us to spend meaningful time together. In the past, I've been in relationships that were quite damaging to me, and I went through a phase of being a heavy stoner when I was younger. But I’ve managed to completely turn my life around; I now have a home, a car, and a stable job. The only addiction I still have is coffee. For a long time, I've had feelings for her and a strong desire to protect her, but I used to dismiss these feelings, convincing myself they were just a result of my past traumas or my stoned state. Recently, as we started hanging out more, she began dating a guy who's over a decade older than her. There are many reasons I’m not fond of him, but as a friend, I want to support her. I always try to provide a different perspective because her happiness is important to me. However, I worry that I’m justifying his behavior to her out of fear of expressing my true feelings, and I’m scared of losing her or discovering that she reciprocates my feelings but would be better off with someone else. I know it's not advisable to ask general questions, but I'm feeling lost—what should I do?