@lilyblue,
A few thoughts:
- there are quite a few ex-wives who genuinely try their best to make their ex-husbands lives a living hell, once they find out that their ex is in a relationship
- those sort tend to try and turn the kids against their ex's. When the father lives a long way away, it's very easy for the mother to make up stories that kids will believe.
- as he lives a long way away, it would be quite easy for her to deny him access to the kids (just go away for the weekend, or have them out one a 'day trip' or any number of things). Even if she just didn't open the door to him - the redress for such tactics is long winded and difficult...which effectively means the same thing (he doesn't get to see his kids)
- he may have moved away for the above reasons - he wanted to start over but knew it would be impossible in the same town
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All of that doesn't explain that he's paying his child support out of your joint accounts. Quite seriously, if he doesn't want you involved in any way in their lives, then that should include finances too.
I would suggest that if it bothers you, and can't be resolved through negotiation, that you go down to your bank and create a separate account to put your pay into. Then you can set up an automatic transfer to put money for the bills/mortgage into the joint account.
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And on another negative side :
Why would she send 'I love you' to cause trouble if she doesn't know about you?
I would consider the Private Investigator if you can afford one. (though why people accept this and not snooping on computers, I will never know - PI's are much more invasive)