my divorce order allows spousal support to cease when my ex receives her inheritance.

My ex has joint accounts and investments with her elderly parent. My divorce order allows me to apply for a material change when she receives her inheritance. She is the sole heir and beneficiary.Under the presumption of advancement this money should be equally and rightfully hers. This would put her net worth 300k more than my net worth. She also lives with her boyfriend in a mortgage free home and he earns much more than me. They are fighting my request of a material change in circumstance. They have been arguing for almost 2 years. It is going to Case Management Trial. Any advice would help.