Brexit Divorce Papers Filed. Insane Bill Sent.

Today Britain has officially triggered the E.U. exit clause.  The E.U. responded vindictively.

Britain has officially launched the Brexit process, triggering Article 50 and starting a two-year countdown before the country drops out of the European Union.

The historic moment came as a letter signed by Prime Minister Theresa May was delivered to the Brussels office of European Council President Donald Tusk, notifying him of the UK’s intention to leave.

But the E.U. responded like a jilted lover.

As in many divorces, the first area of conflict is likely to be money. The EU wants Britain to pay a hefty bill -- Jean-Claude Juncker, president of the EU's executive Commission, put it at around 50 billion euros ($63 billion) -- to cover pension liabilities for EU staff and other commitments the U.K. has agreed to.

Britain acknowledges it will have to pay something, but is sure to quibble over the size of the tab.

Negotiations will also soon hit a major contraction: Britain wants "frictionless" free trade, but says it will restore control of immigration, ending the right of EU citizens to live and work in Britain. The EU says Britain can't have full access to the single market if it doesn't accept free movement, one of the bloc's key principles.

Both Britain and the EU say a top priority will be guaranteeing the rights of 3 million EU citizens living in Britain, and 1 million Britons living elsewhere in the bloc.

The two sides also appear to disagree on how the talks will unfold. EU officials say the divorce terms must be settled before negotiators can turn to the U.K.'s future relationship with the bloc -- and a deal on that could take a decade. British officials want the two things discussed simultaneously.

Like most divorces, this could get contentious.  Suggesting Britain owes $63 billion for E.U. staff pensions and "other commitments" is a good indicator of why Britons voted to exit the E.U.  If that's just the U.K.'s share of pension obligations, the E.U. cannot possibly think of itself as sustainable.