Ex hubby's new wife is getting in the way of me and my son

So my husbands new wife is getting on my last fucking nerves. She's closer in age with my son (Shes 23, hes 17) than she is with us so I expect her to encourage bad behavior. But it's the fact that my husband does not put her in her damn place that pisses me off. In January my son asked me if he could buy condoms. I said absolutely not you're too young for what you're thinking about and he said but I've done it before. I said so you're admitting to either sneaking a girl in my house or having sex in public? And he went silent so I added a monitor on his phone and life360. Maybe a week or two later I found out he had condoms anyways. I asked where he got those from and he said Melanie (Stepmom) gave them to him. Then in February, he wanted to dye his hair to blond. I said absolutely not and he went off and complained to Melanie. She called me and was like "Why can't he dye his hair? He's almost an adult and you act like the poor boy is in middle school" I respectfully told her to mind her business because she doesn't know shit about teenagers, especially since she was just one not too long ago. Yesterday my son was on the phone with her talking about how he wanted to surprise his girlfriend with something special once the quarantine is over. I asked him why he didn't he talk to me and I told him I give pretty good advice about girls. Melanie, who was on speaker, told me "Generations have changed" in a snarky voice. I told my ex husband that he needs to keep his wife in check and stop trying to parent OUR son. My ex was just like "If he feels more comfortable with her than you then he just does and there's nothing you can do about that" I'm just so tired of the both of them and I'm close to making my son cut off contact with them.