AITA for telling my step brother to suck it up after his baby died

My step brother cheated on his wife who he has 3 kids with and got another woman pregnant. Honestly his wife is an angel because this woman was awful to her, yet she still moved her in to make sure she was taken care of because she was living in a bad environment. Well she got them sleeping with each other again even though he said he wanted to save the marriage. Obviously not. But she still tried to help so she paid her his baby mamas apartment. The deposit, first 4 months of rent. Etc. because she didn't want her in her home anymore but still wanted to help her get out of a bad situation. Fast forward, they lose the baby at 38 weeks... She had a stillbirth. Everyone was in pain including his wife because they were going to adopt his baby mamas baby because she already lost one child to CPS for child abuse and didn't want them to take her other child and put them in foster care. Even though she lost the baby my step brothers wife still paid for her to keep her apartment for another few months. Even though my brother quit his job due to depression. So she was taking care of his mistress and the woman didn't even appreciate it. Well a month after they lost that baby his wife found out she's pregnant. She's 5 months pregnant and has been going through it all alone because he's grieving his other baby. And his mistress went and harassed his wife at her job. She's been put through so much. He also went to go have sex with her again to "feel close" to the baby they lost. His wife won't leave guys... They have kids together. She has gone to every doctors appointment alone and found out she may be giving birth alone because he's too depressed. So I told my step brother this is gonna sound harsh. Nobody deserves to lose a child but go to therapy and suck it the fuck up. She had to suck up all her feelings the entire time your side chick was pregnant. She had to put everything aside to take care of your side chick. You let her harass your wife. You don't get to shut down on her now that shes pregnant. Go to therapy. Go to therapy for grief. If you have time to continue to cheat you have time to be there for your wife. But suck it the fuck up and be there for the wife you don't deserve. Was I an asshole. I'm just sick of seeing her get treated this way. She has trauma and bad attachment issues. I gets he's grieving but he caused so much and has to deal with the consequences of his actions and he a fucking husband.

@Jasmine's mum she has trauma and attachment issues along with having autism. She did what she did because she didn't want to blame the child for the actions of the parents and the side chick was in a bad living situation and didn't want a baby in that. I love his wife and even she has said she has a hard time letting go when people treat her badly. It's not that she likes being miserable. She just has a hard time letting go of attachments.

Edit: Listen I don't agree with everything she's done. She has a way bigger heart than I do. I didn't make this post to talk about her choses because she's done them and there's nothing I can do about that. If she wants to stay with him then okay. All I was asking is if I was wrong for telling him to suck it up when he lost his baby. It's not really about saving her. It is more about calling out my family member when they're being fucked up.