Prescribed Hydroxyzine for anxiety and worried about side effects.

I am a 35 yo female, and have had severe anxiety for many years now. I’ve tried OTC stuff and it doesn’t do anything. A lot of my anxiety comes in social settings, and it’s a whole body experience that I cannot control. I’m talking body tremors, heart racing, sweating, feeling like I’m going to faint and vomit at the same time, etc. I also happen to have iron deficiency anemia, and I think because of this I get heart palpitations/fluttering. I just saw a new provider today and told her about the anemia and anxiety, and she prescribed me hydroxyzine 10mg to take on an as needed basis. After researching it, I’m paranoid about the potential of having “qt prolongation”. I do have family history with heart issues and I did mention that. This is why I have never asked for meds in the past, because I get anxious over the side effects. What is the likelihood of this happening and how serious is it?