My partners mistakes

I've been with my partner for over two years now, when I met him I was leaving a domestic violent relationship that went on for 10 years ( he was only violent towards the end of it) so my current partner in my eyes was my saving grace. Had he not come into my life at that time I may or may not have stayed with my ex. Upon meeting my new partner he gave me the strength to get up and leave because I just knew I didn't want to go back. Anyway he was absolutely amazing everything was great I was really so in love with him, 6 months into our relationship I find out I'm pregnant. Huge surprise and so happy and knew it was meant to be... 9 months into relationship I find out my partner had an addiction to drugs that I honestly had no clue about. He knew how I felt about it ( from general convos et ) so he did everything in his power to keep it from me. The day we were moving into our place together I found out the truth. His friends phone was left at our house and I had no idea who's it was and when I went into it the last thing was FB messages between my partner and his best mate talking about getting their stash etc....
Honestly it was as if my whole world around me came crashing down, I was shaking and crying and honestly heartbroken and I felt as if everything had been a big fat lie!! I was about 3 months pregnant and too late to have an abortion so had no choice but to try Atleast for the baby. A lot went on and I had to inform his family etc of his problem so they could also help him. He eventually went to rehab as he knew he would not be in my or the babies life had he continued to use it.. I'm proud of him for being so strong to stop his use for us, it is all around him and I honestly couldn't imagine how hard it would have been for him but he did do it. Only problem is now I have severe anxiety issues, where I get déjà vu or a song or moment would remind me of what I went through back in 2014 when he put me through all of this. I have forgiven him, our son is almost one now and the last time he used was November 2014 however I still have panic attacks or think of things he put me through and I hold it against him? I constantly bring up old things to remind him what he did or said to me during that terrible time... It was back in 2014 and we have come a really long way and I know he wouldn't use it again because he is a completely different person now however I still get freaked out by certain things. I don't know how to control the urge but the impact that being in a relationship with an addict had an immensely huge effect on me and it is still something that is bothering me today... Although I know I found the love of my life in 2014 I also feel like it was the worst year of my life because of what I went through.
What should I do? Should I see someone? I feel bad constantly bringing it up to my partner when he wants to put it behind us??? HELP