Do you treat your anxiety disorder? That's probably going to be a positive for this situation if you do and if you don't, perhaps that is an area to explore?
Have you checked the potential side effects of your meds? Being on one med is hard enough, but to be on 3 gives you 3 chances to get side effects from them, so it's possible some of your problems are from one or all of the meds. Might check that. I would recommend you try meditation. It might just help you relax you whole system, not just your anxiety, if it works for you. The two most studied in the West are TM and Mindfulness. They are best learned from a spiritual believer, though you don't have to believe in that part of it; they just know best usually how to teach one to do it. What are you doing to treat your anxiety? Therapy? Medication? As for exercise, if you can't stand up without a problem, that's going to be hard, but are you sure your heart rate is going up or does it just feel like it is? A lot of anxiety sufferers think they have heart problems, but most don't. It could just be anxiety rearing its ugly head. But there are people who don't breathe properly when they are anxious and this shallow breathing can cause problems. Some hyperventilate during an anxiety attack, and then when they exercise because it feels like the anxiety attack did as your heart gets going the problem can be the anxiety kicking in, not the exercise. Your physician who is treating you for the BP can tell you better if it's safe for you to exercise and might recommend which types are best to start with. I was always able to exercise heavily, but my sister, who had a similar anxiety problem, had the breathing problem. I never did, maybe because I meditated regularly, I don't know. She was also quite obese and I wasn't, so it might be that. But it just shows, different people have different reactions to anxiety, and it can also change over time. If you want to exercise and it's safe for you to do so, pick something you like to do and then do it. If you're able to play a sport, having fun might allow you to forget all about your anxiety. Start slow and work your way up. But you do have to do something about the anxiety, and therapy is usually the place to start. Peace.