Advice please; Son being bullied because his mother spreads vicious rumours.

Sorry for the long post.
Just found out my son 9 years old has been bullied for the last 2 months.
My ex (mother of my children) informed me today after picking up my son and her being surprised about his apparent “happy mood”. I explained that he was a little quiet but after half an hour he was like how I would describe he normally is, ie energetic, making jokes, talking about his hobbies and sports.
When his mother came to pick him up she informed me of the bullying as she was apparently surprised about how happy he seemed to be. Then went on to tell me that he is being bullied at school and kids are calling him a loser and his father hates him and that’s why his parents broke up (yeah kids will be kids).
I pointed out to my ex that these kids must have heard it from their parents, and therefore someone (her) must of been gossiping/fabricating lies about me.

How do I navigate this? I don’t care about what she has said about me, but when it opens up my children to be any easy target for bullying it’s not on. P.S this happened 2 years ago with his older brother too.

reddit.com
u/Negative_Reveal811 — 11 days ago
▲ 11 r/drugextraction+2 crossposts

Magnetic stirrer and hot plate? Need advice/past experiences.

As the above mentions I’m looking at replacing my old one which I got off my grandfather years and years back. For those who know what would you do recommend?

Thanks

reddit.com
u/Negative_Reveal811 — 14 days ago