Would you keep talking to your mom if you were in this situation?

Okay, this may be a long post, so I apologize now for that.

My mom remarried about 10yrs ago and I HATE the man she married. She was so hurt by my dad's cheating I feel like she rushed into marriage. She didn't even take the time to make sure my brother and I were ready for her to start dating, she just waited until the divorce was final, then expected us to be happy she was dating and welcome him in like nothing was wrong. She also refuses to see our side of the situation. I tried to point it out and we didn't talk for almost a year because she wouldn't listen and insisted we just weren't happy that she wasn't being treated like shit by our dad anymore.

Anyways, fast forward a bit and my brother is now a father to 2 girls at the moment, and his family are living in my mom's garage as they had nowhere else to go. Well my SIL was breastfeeding my niece and it was during the summer, so she had a couple doors open for airflow and she was facing away from the door since she wasn't wearing a top, but was in her room. Anyways, she starts to get this weird feeling and turned and saw my step-dad in the doorway staring in her direction and after a moment he shakes his head and starts "looking" for his daughter's cat.

Well, she waited until they moved out about 6 months later and into an apartment with me before saying anything to my mom. My SIL has a history of trust issues, so it took my brother to get her to tell my mom what happened. When she did, my mom did "investigate" and didn't find any "proof" that her husband is a pervert and then called my SIL a liar.

Now it's been about 6yrs since and they have been fighting off and on to the point my brother and mom have disowned each other like 4 times (I lost count honestly) and I've been the middle person this whole time.

I've tried to get my mom to see my SILs side, but it's like trying to explain things to a brick wall. So now my SIL and brother don't allow my step-dad near their now 3 girls (which I don't blame them at all) and my mom has yet to meet my 3rd niece who is going to be 4 soon.

I don't think anything is going to change until my step-dad is in the ground, but I'm just wondering, do I tell my mom that he made me uncomfortable a few times as well? Like I visited after having my son to spend Christmas with my mom and everytime I went to breastfeed my son, felt like I had to hide in the bathroom or my car to feed him if my step-dad was in the living room with me (I even had a cover on) and felt like it wasn't enough. My son is now 3 and talking to my mom is like walking on egg shells. She wants my son to call her husband grandpa and I don't, but don't want to offend my mom. I don't want her to burn the bridge with me too, but I hate walking on egg shells with her all the time. My dad says I shouldn't say anything, but I can't get it out of my mind. But I also fear if my mom burns her bridge with me that she will get so depressed that she may commit suicide (she has BAD depression).

Please don't give me crud for dealing with this for 6+ years. Just tell me what you'd do in my shoes. Thanks y'all. Sorry for the long post and thanks if you read it all.