PTSD is ruining my relationship

I'll try to keep this as short as possible. I really need help, I'm in a state of panic.

My step brother was abusive. Physically, verbally, and sexually. The last rape incident to take place was a little over a year ago. The last physical attack and sexual abuse took place last October. So I am nowhere near being recovered from my symptoms and such.

I am triggered very easily. Loud voices, angry people, sudden movements, swearing (especially if it's aimed at me), or even someone getting too close to me will send me into a wave of flashbacks and memories accompanied by severe anxiety. if the situation feels unexpected to me. Internally I am triggered by nightmares (which happen often) the feeling of being tired, feeling like I have no control, etc.

My boyfriend, who I have been dating for 16 months now, has grown impatient with my ever prevalent crying spells, anxiety attacks, timid moods, and flashbacks. He used to hold me and comfort me but now he sits back to watch and wait for me to "get over it". Which makes me feel 10 times worse. He once said it's because he thinks he's the one causing me to act this way. I've tried countless times to convince him otherwise.

How can I get ahold of my symptoms? Stop being triggered by things? Learn to control my emotions and not act out like that? Any advice would really help me. I want to fix this relationship.