AITA for Not Wanting to Pay Child Support After My Wife Cheated with My Older Brother?

His wife cheating with his own brother would have been devastating enough. But for this man, the fallout didn’t stop there. After five years of marriage and slowly drifting away from his extended family to focus on building a life with his wife, he discovered the ultimate betrayal—an affair between the two people he should have been able to trust most.

Before he could even process that, another shock hit. She told him she was pregnant—and insisted the baby was his. While his mother urged him to “be a man” and move on, he found himself stuck on one question: is he wrong for demanding a DNA test before agreeing to pay child support?

‘AITA for Not Wanting to Pay Child Support After My Wife Cheated with My Older Brother?’

Everything started unraveling when what seemed like a stable marriage suddenly cracked:

When he turned to his mother for support, her reaction only deepened the wound:

As if that wasn’t enough, another bombshell followed:

Torn between anger and responsibility, he asked:

At the heart of this situation isn’t just child support—it’s shattered trust. Discovering a partner’s affair can be deeply destabilizing. When that affair involves a sibling, the emotional impact often cuts even deeper. Psychologist Shirley Glass, author of Not “Just Friends”, has written that infidelity can create trauma-like symptoms, leaving the betrayed partner questioning their entire reality.

From a legal standpoint, child support is about the child’s well-being, not the parents’ relationship. If a DNA test confirms paternity, financial responsibility is typically unavoidable. Given the circumstances, however, requesting a paternity test is entirely reasonable.

Some argue that personal resentment shouldn’t interfere with parental duty. Family counselors frequently emphasize that children should not become collateral damage in adult conflicts. If the child is biologically his, separating anger toward his ex-wife from his role as a father will be crucial.

A practical path forward would involve three steps: confirm paternity through official testing, consult a lawyer to understand custody and financial options, and seek therapy to process the betrayal. Clear legal boundaries and emotional support can help him make decisions rooted in stability rather than rage.

These are the responses from Reddit users:

Social media users quickly weighed in—and most agreed on one thing.

Many strongly supported getting a DNA test first:

Others encouraged him to take even stronger action:

Some focused on legal and mental health advice:

And of course, a few doubted the entire story:

Caught between betrayal and responsibility, this man is facing an impossible emotional crossroads. Wanting a DNA test before committing to child support seems like a rational step in a situation clouded by deception.

Still, if the child is biologically his, the conversation shifts. At that point, it’s no longer about his ex-wife—it’s about an innocent child. What would you do in his position?