sorry to hear this, not happened to me, but some close friends had similar issues
they moved back in with their parents, not ideal as an adult, but only way to save money, and pay child support etc
also, wasn't ideal when kids came to stay, but they worked round it kids in his room, him on sofa for weekend etc
BIG thing, don't slag the ex off to your kids, if she says bad stuff about you to them, don't get revenge, don't call her a liar, but explain it's not all black and white or that simple.
it's taken a while, but now one of my mate's kids are older, they can see the truth, and know they have one manipulative parent, rather than two - btw the kids have turned out great despite the crap them and their dad was stuck in - he's in a great place now,met a nice lady, settled down with her
so take your time, get proper advice from professionals, citizens advice etc not just hearsay from ppl like me on the internet
personal experience is obviously useful, but sooner or later there will be contradictions etc
good luck, if you need help that's fine, you've said you need councilling - good, not good you need it, but good you know you need it, and fingers crossed they help you