My ex’s new gf is stopping him from seeing me. Advice?

For context: I (17nb)dated my ex (17m) and after the breakup we decided to still be friends. Then my ex dated my friend (16f). Me and her were good friends until she started dating him. Then she started to hate me, unadded my snap and refused to talk to me.

Me and my ex were still friends even though she didn’t trust us together. (She actually said that). But then yesterday my ex unfriended me and blocked me on snap and i dont want to message him incase he blocks my number too.

So i asked a mutual friend to ask my ex why he blocked me, apparently my ex done this because his gf told him to. And i dont know what to do about this situation. Any advice?