It seems like your son has a healthy long term interest in lacrosse. I encourage you not to let any negative dynamics cause you to lose awareness the positive things the sport brings for your son and family. I understand that having a sport of mutual interest between the father and the son can strengthen their relationship.
I see how hard it is for my son to know how to act when he is around both me and his dad. With me, my son is able to show his emotions and we are able to talk about anything.
I think this communication's openness is good.

When his dad is around, my son reverts into a mini-him and talks to me in the same disrespectful way his dad
does (almost trying to impress him).
Can you get specific about this disrespect in terms of actions and topics?
I took all violent episodes seriously and eventually he stopped actually hurting us.
Your role in reducing the physical violence of the family is good to uphold as a very good thing.
The problem is that we were already conditioned to fear him... . I guess the fear of all that still controls us.
Yes, you may still feel fear as a consequence of this history between your husband and you. As what Turkish suggested, I think "reflecting" here would be beneficial for you to use. What reflecting describes is when instead of absorbing the pain or anger from him, you "don’t soak it in, but deflect it off you" (Kreger).
Reflecting in this way can take various forms. What one form looks like is to keep your feelings separate from the other person. This acts against projection of feelings. It means to be aware of whose feelings are whose.
For example:
BP: →
You spend all your time at work, you don't love me.← If you really loved me you would come home sooner. Show me pictures of the women in your office. Forget it, I'm leaving. Don't come find me. I hate you.
→
... .you don't love me.←
The
feeling here is loneliness. Her expression of loneliness is taken as "absence" of "love".
→
You spend all your time at work ... .←
The
fact may be I spend a lot of time at work. But this is different from "all".
In the example, we've got assorted feelings of loneliness, fear, sadness, etc. To reflect is to be aware of whose feelings are whose. I'm calm. She's angry. I check to whom each feeling belongs. From whom did they start. To whom does the consequence move to.
Now--at this point--I'm
better able to choose my next action. I can (1) get drawn in, (2) simply listen; other responses.
Examples from your situation.
1.
If he shows his angry face, you can observe to yourself "ok,
he's angry", then choose your action from here.
2.
If he seethes, you can observe to yourself "ok,
he's angry", then choose your action from here.
3.
If he uses a gorilla voice, you can observe to yourself "ok,
he's angry", be clear in your mind's eye
he's angry, then choose your action from here.
I know boundaries need to be set. Would love suggestions!
I suggest one you can start with is "I've got a right to be responded to with courtesy and respect". To reflect as above is one way you can enforce this boundary. This enforcement comes tacitly. It conveys that you are neither simply taking his anger nor treating it as a given. To clarify, look at each of the above and observe the boundary at work:
1.
It's not respectful to me to be repeatedly met with aggression.
2.
It's not respectful to me to be repeatedly met with passive-aggression.
3.
It's not respectful to me to be repeatedly responded to aggressively.
Simply by identifying the anger, you're now aware that this is an opportunity to observe the boundary you set.
