Based on what you tell it is not likely that she divorced you, but it is possible and you should check. However If she specifically said she didn't divorce you there is little doubt about that. In all likelihood she took the easy way out with her marriage to you not registered in Thailand, with now serious consequences for her.

I hope she doesn't have children with her other spouse, which will complicate things in an already complicated situation.

I would get a divorce as soon as possible.

She has a young child in EU by another man - don't know who. Is this likely to offer her some kind of 'protection'?

In first instance only problems, as first must be determined who the legal father of the child is. Normally that is the person she is married to... It will now depend on in which country she was married for a second time and which provisions that law makes in case a marriage is void. He could very well remain the legal father despite the marriage itself being void. That is a common solution and will probably the case.

If the other person is the legal father, it might give her some protection and could be a reason to grant her permission to stay. But that is not to say that she didn't commit a criminal offence. However, she didn't maintain two relationships/families at the same time and that will count. But her right to stay will be a mess and she requires very competent legal aid for herself.

You live and work in Thailand. There is no record of your marriage in Thailand. Your wife from 100 years back lives overseas with no plan to go to Thailand. Why even worry about it unless you plan on taking your new wife to Europe. Why get married in the first place? You didn't learn the first time?

You live and work in Thailand. There is no record of your marriage in Thailand. Your wife from 100 years back lives overseas with no plan to go to Thailand. Why even worry about it unless you plan on taking your new wife to Europe. Why get married in the first place? You didn't learn the first time?

I want to marry my current Thai partner (10 years together, we have a child). I would like to return to UK with her as my wife. The first marriage went bad, but I wouldn't assume that all marriages end up that way.