I'm very sorry for you. I think it's important you contact his therapist. It's possible your husband doesn't really notice this change in his behaviour and relationship and therefore didn't tell the therapist. And the therapist isn't only there for him, it's important they also support the family, especially when the therapy has so much influence on him.
It's possible that he's recalling memories that aren't completely true. Little details could have changes, making you for example say something hurtful. It's also possible that, because EMDR is very intense, he gets into this circle of negative thinking. For example, he starts to be suspicious of you. Thinking you may be out there to hurt him. Because of the things he recalls in his head, this will make the belief stronger that everyone, or you, are going to try betray him too. He acts out and you get into a fight and for him and because of his thinking circle this will give 'prove' that this might be true. This doesn't mean it's your fault. It's very tough for the both of you and even though his behaviour may be undestandable (because of the EMDR), it's not acceptable.
Maybe it's possible to have a session together, or a talk session together. It's important that you get the change to find out what his cognitions are. Then you might be able to explain why you acted in a certain way (and why that wasn't to hurt him) or explain what happened back then, if you think he's accidentally remembering it a bit wrong.
I don't know if you ever met his therapist and how your and his relationship with the therapist is, but I've also had therapists who (we find out later) were trying to break a wedge between me and my partner. We've both been in therapy and we've both encountered those people, even though we're a great match and very supportive for each other (he has changed my life in many positive ways). Because you're already extra vulnerable and irritable and thinking about a lot of negative things that happened in your life, when a therapist starts to doubt the behaivour of your partner, that has a lot of impact. More than if you could think clearly. We really had to discuss what the therapist said and if that was true or not. My partner went with me to sessions, because of the wrong cognitions the therapist actually had. I hope this is not the case with your situation and it probably hardly ever happens, but I did feel like I should tell you. In my and my partner's case it wasn't with EMDR therapy.