Looking for a bit of advice if you could, hopefully from people who have been in or have experience of similar situations.
Back story first, my wife and I have been separated for 12 months and have an 8yr old son. Pretty mutual separation, she ended it so I moved out but I'm only a couple of streets away, we have an informal arrangement where he stops with me 3-4 nights a week, alternate weekends and I accommodate if she has weekend plans and vice versa. Currently I pay about 50% more than CSA advise, again informally and for the most part it's been working fine.
Yesterday morning I had a knock on the door and it was ex wife, clearly distressed. All she has said so far is someone from work came round (male), there was an argument, he's grabbed her arms and bent them behind her and snapped her phone, which she has shown me and there was some serious force involved. She won't say who it was, although I know, and from speaking to my son he's been in the house when he's there. I suspected she was seeing this guy shortly before we split and have had my suspicions something has been going on since, although he's married, 3 kids etc. However I've no interest who she sees as long as I'm informed before they have any contact with my son.
How do I play this now? This was due to be her weekend with our son, he was with me Friday night, but for obvious reasons he has stayed with me since and is due back today. I can't stress enough that it's not her seeing someone that's the issue here, it's that my son could witness someone being violent with his mum. She says this is the first time anything like this has happened and I've no evidence this isn't the case but there has been a noticeable change in her personality of late and know she is not being truthful about what happened. Clearly this guy has some sort of emotional hold over her and I can't trust that she won't continue seeing him and have him round when our son is there.
Thanks in advance, a concerned father.