The baby mama

If any of you women have any experience with this in any way, please give me your opinions. My boyfriend has an 10yr old son. He never used to see his son because the mother is crazy, but a few months ago he started getting him every other weekend again. The majority of our relationship, his son wasn't really in his life. I always knew he had a son, but now it's so much more real. And at times, it's really difficult. Mainly because I want a child with him so bad, and to see him have that with someone else kills me. We plan to have a family once I finish school in a year or two, but i almost wish I could have one now. Not to mention, the mother hits on my bf all the time. They had only known each other a couple months when she got pregnant, so they were never in love or anything. She calls him every single day, at least 2-3 times a day. If he doesn't answer, she says its an emergency about the son so that he will answer, and it's not. I get along great with his son. But she is jealous of me since I am with my bf and he wants nothing to do with her, so she says she doesn't want me around when he has his son, otherwise he can't have him. I'm nothing but a good influence to her son. I help him with his homework, cook for him, play with him, my bf and I do these things together with him. We never do anything inappropriate in front of him. There's no reason for me not to be around him. And there's no reason for them to talk every single day throughout the day. I understand maybe once or twice a week to talk about the son, but his son has his own phone too so he can talk to him directly.  Am I crazy for thinking this and being upset about it?? My bf is afraid to tell her off completely because he's afraid of her filling her sons head with stuff and not letting him see him anymore, even though the court granted his time with him and he pays child support. His son has a good time when he comes over, but his mother is very manipulative of him. She's always saying bad things about me, what can I do in this situation?