I don't want to lose my best friend.....Help?

She's been my best friend for a long time, she's great, but she's also blunt on her feelings...I got a boyfriend about three weeks ago, and I've been neglecting her for a long time, whenever we'd made plans I'd ditch them to hang out with my boyfriend. So we haven't hung out for a long, long time. Even before I got a boyfriend...I said yes to him because the guy I liked said no to me, but i do think i really love him...but the other day she made plans with me so it'd just be us two..but the day before my boyfriend said he was coming over the next day, and i didn't really care if she was there or not so I said yes. I didn't talk to her much that day either, i was busy with my boyfriend..and she told me that she was feeling even more neglected, she understood that i had a boyfriend, but if things go on this way, she'd leave me. i told her things would change, but they never did...it's still the same thing we're talking less and less. and she said she's closing to leaving me, she told me that she doesn't even see me as a best friend anymore..i can't put all my time on her all the time :/