Crosspost "AITA For Agreeing With My Brother's Ex-Girlfriend?" from /r/AmItheAsshole:

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I (34f) have a young brother "Tom" (30m) who is co-parenting my 4-year-old nephew "TJ" with his ex "Amanda" (30f). She and my brother had known each other since middle school and dated off and on in high school. It wasn't until after college that they decided to get serious and moved in together, they were even engaged and would've gotten married if Amanda hadn't of found out she was pregnant. The dream dress that she wanted to wear was not made for a pregnant woman's body and opted to wait until after their son was born for the actual wedding.

Everything seemed to be going great until Tom decided to toss a grenade into the relationship by asking for a paternity test before signing the birth certificate. He admitted that he had no proof nor did he suspect Amanda of cheating and believed that their son was his but wanted to be 100%. Obviously Amanda didn't take too kindly to what was being implied and moved out while Tom was away at work. A few days later he got the ring back through the mail along with a court summons for child support, which included the DNA he initially wanted.

Tom was the father and while there were people on both sides trying to push for reconciliation Amanda wasn't interested. She was mostly civil about everything but refused to engaged with Tom about anything that didn't directly involve their son. To me she didn't seem angry just cold, like she could put on this convincing mask of warmth and joy with Tom whenever TJ was around but the second he wasn't she would go "please don't touch me."

Tom has always been hurt over how Amanda responded to his request and feels that she failed TJ by walking away instead of just staying in the relationship. I mostly just bit my tongue but now that Amanda has started dating again Tom has gotten worse. One day he was ranting about how it was too soon for Amanda to be dating. I responded by bringing up how Tom has had at least two girlfriends since his relationship with Amanda ended. Tom defended himself saying that what he did was different as he was just dating to have fun and "scratch an itch" while Amanda is looking to marry. Eventually, I got fed up with his attitude and told him that the only reason he's in this situation is because of choice to question paternity. Tom said that as a man he had every right to know if TJ was his and I countered with Amanda having every right to leave him over it, as no honest woman should have to be treated as if they've done something wrong and that I would've done the exact same thing as her if a man ever dared to try something like that with me. Since then my parents and a few of Tom's friends have said I was in the wrong as my brother was looking for a sympathetic ear rather than being kicked while he was down. AITA?

Posted by Agreeable-Scholar762 | 13 August 2021 | Link