Ex wife hates me

Hi everyone,

So I need some friendly advice, my boyfriend and I have been together for over 2 years now and I am just now getting involved in his sons life because we wanted to wait to make sure it was serious before involving the kids. I even sat down with his ex wife and went over ground rules with her and everything seemed perfect so finally yesterday we have the boys over, the oldest is 8 and we baked sugar cookies together just to get to know each other. It went super well and the boys really enjoyed themselves. I thought their mom would be happy about the boys enjoying themselves but she wasn't. She threatened to beat me up and pretty much threatened my life. I am just so confused because I followed all the ground rules, waited for over 2 years. Any advice from women on the other side with ex husbands who have girlfriends? I just want to know what I can do to make this easier on everyone.