In my opinion, the text was a bad idea. Remember, she left you. No need to play Mr. Nice Guy with her right now. She will end up walking all over you anyway.
You know how I manage to stop myself from texting or calling my MLC'er? I always say to myself
' F her'
It works 100% of the time. Trust me, it feels good to say it.
Right now, focus on yourself and your kids. Let her continue on a downward spiral. Just don't let her suck you or the kids into it along with her.