Boyfriend with anxiety, anger issues, and panic attacks

For a while now I have been trying my best to help my boyfriend stay under control being that he has panic attack’s randomly and can get easily angry. The past couple of days he’s been really happy but it’s a pattern...he’s depressed for about a good month then somehow is happy again and it usually will last for two weeks. He used to be on medication but he stopped taking them because he didn’t feel ‘normal’. I love him and I want to help him but sometimes I feel like I’m not doing enough or I’m not responding the right way when he starts to have panic attacks or his anxiety kicks in. I don’t know how to help him being that when I had panic attacks just yelling to myself “Im okay” while taking deep breaths ended up working. I’m worried about him because I don’t want to make it seem like I’m giving up on him but I’m running out of ways to help him. He’s recently gone to talk to a therapist because he’s bottled everything up inside. He’s a victim of rape and was neglected as a kid. He said letting it out helped him but how do I know he’s actually going to get the help he needs? I’m not trying to change him or make him go on medication. But I want him to realize that what happened to him when he was younger shouldn’t take over the rest of his life. I was raped by my own grandfather and to this day only three people feels great to say it here because no one really knows me but I’ve never let it take over me like he let it take over him. I just want to find a way to help him...any suggestions how?