I've been experiencing anxiety attacks lately and it came to the point where I was having intrusive suicidal thoughts because I was tired of being anxious all the time. I started doing breathing exercises 3 times a day (push your belly out when you inhale and in when you exhale, do it for 5 minutes 3 times a day, inhale for 4 seconds and exhale for 6 seconds) it helped for a fee weeks but the anxiety attacks kept coming back so... what you need to do is:

1. Sit down with your back straight and your eyes open, focus on a harmless object and put your attention on your breathing, try to slowly breathe in and out, it's gonna take some time but keep trying 

2. When you gain control of your breathing, slowly look around you (specially behind you) and tell yourself "I'm safe, nothing bad is happening to me, I'm ok" you need to actually say it because your brain needs to hear it to stop the panic reaction so even if it sounds silly, it's very important. 

3. Take a deep breath and sigh to release pressure a vocal exhale... I'm not sure how to say it in English but you probably know what I mean haha, keep doing all the above 5 or 10 minutes after the attack stopped to prevent it to kick in again (sometimes it comes like panic / anxiety waves so let's prevent a new wave to come) 

That's what's been working for me when i feel I'm gonna have a crisis, and when you feel the previous symptoms like sweaty palms and your heart beating like crazy don't try to stop it or fight it (I know it sounds crazy but bear with me) it's just a uncomfortable feeling that will eventually go away but if you try to fight it it'll just get worse so, just let the anxiety flow, focus on what you're feeling and write it down, that helps the brain to process and resolve emotions. 

KEEP IN MIND this is gonna help you in the long term, if you keep practicing, some guided meditation and visualization exercises might help you as well so, take some time and try different things and don't fall into despair, you're gonna be OK and eventually the attacks will stop. &lt;3