I am non-custodial parent who pays full child support while custodial parent does not work and on welfare. Can I claim my children on my tax return?

For the last 14 years, custodial parent always allowed others to claim our children on their tax return to gain a monetary benefit from it since she never works and live off my child support and welfare. Well, enough is enough and if she is not claiming them, am I eligible or at least has the right to claim them on my tax return since I am the only one who financially support them 100% of their lifetime.