Is it cheating? Did Becky cheated on my cousin?

Anonymous
My cousins girlfriend gave birth to a baby and she said the baby is 8 mos. Premature So my cousins sister is a nurse who has friends with said hospital where my cousins girlfriend gave birth. She asked if there's delivered baby 8 mos on that day my cousins girlfriend (lets call her Becky) and her friend said all babies that were born on that day are all 9 mos. So they asked Becky (cousins girlfriend) if that baby is my cousins? She said the father of baby is from her ex husband..
So it means becky is still seeing her ex husband while being in a relationship with my cousin. by the way Becky has 2 teenage kids with her previous husband. so does that count as still cheating?
by the way my cousin works at ship and has high salary I wonder if Becky is doing that to make my cousin stay? My cousin is not single either he's a single father just like her.
Is it cheating? Did Becky cheated on my cousin?
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