Dating a guy with baby mama

So I am with the love of my life and he had a baby with his ex and she left him before she had the kid, and now the baby is 8 months old and the baby mama is starting to talk to my boyfriend and wants him to be I her life now but wouldn’t allow me to be around the baby

I met her once and she made a big deal about it but now she won’t even let me see her with him and all I ever want to do is be there for him and be the best step mom I can be

I bought her a lot of clothes and gift but we gotta make it seem that my boyfriend bought them so she will take it,

I don’t know what to do or if I should even try with her since it’s her baby and all