My STBXH's girlfriend's XH apparently is violent

[cw68]

OK, this morning I get a text from my STBXH asking if I contacted his girlfriend's ex-husband as someone called him last night telling him that"L" is dating. It wasn't me.

(I do hate this gal, she's the one that my STBXH was having, at the least an emotional, affair with last fall. Very conveniently, they "reconnected" after I moved out of the house and he was pulling together divorce papers.)

Anyway, STBXH is concerned because this man was making threats to "L" and past incidents leads STBXH and "L" to believe that he could followed through on them. I don't know what the threats were.

Here's where I'm concerned. STBXH says that this guy doesn't know who he is, but what if he finds out and confronts my STBXH when he has my kids? I had already arranged a meeting with my attorney for tomorrow, but can anyone give any tips on what to do?

I'm pretty concerned that his girlfriend's ex is violent and whatever potential negative consequences this poses for my children.