I pay for allof my expenses except i live with ex who pays all the bills for the house and mortgage, can he claim me as a dependent?

It appears from the information that he did not provide more than half of your support. In this case, he cannot claim you as a dependent.

In any case, if you had income of more than $4,150 in 2018, he cannot claim you as a dependent.

I don't think it's clear yet whether you provide more than half your own support. But the support test is academic, if you had more than $4150 of income in 2018. See the full rules for claiming a dependent, below. If the other 5 tests are met and it comes down to the support test, The IRS has a worksheet that can be used to help with the support calculation. See: http://apps.irs.gov/app/vita/content/globalmedia/teacher/worksheet_for_determining_support_4012.pdf The support value of a home is the fair market rental value, plus utilities, divided by the number of occupants. Providing the home usually means he provided more than half your support.

A person can still be a Qualifying relative dependent, if not a Qualifying Child, if he meets the 6 tests for claiming a dependent:

1. Closely Related OR live with the taxpayer ALL year

2. His/her gross taxable income for the year must be less than $4150 ($4,050 in 2016-17)

3. The taxpayer must have provided more than 1/2 his support

In either case:

4. He must be a US citizen or resident of the US, Canada or Mexico

5. He must not file a joint return with his spouse or be claiming a dependent of his own

6. He must not be the qualifying child of another taxpayer