My sister is driving me nuts

My sister (25 F) and I (22 F) have always had a rocky relationship growing up. We didn’t live in the same homes during childhood (same deadbeat mom, different dads) as we lived with our dads. After I turned 18 and we had one of our major fights (I got an abortion while living with her and she kicked me out as she doesn’t support them) so I didn’t talk to her for a couple years until I turned 20 I believe. Our relationship has been better but ever since her last relationship she has been seeing a new guy almost every week. I have given her advice to focus on her and her 2 kids. She FaceTimes me every day and every day it’s always about this new guy she is seeing. She gets real defensive whenever I try and talk to her about it. Anyways, she’s with a guy now and has been for about 3 weeks. He’s already bought her a car and everything (which is INSANE to me as she had issues with her last relationship when her boyfriend got her a car). Now she thinks she is pregnant. It’s only been about a week now since she claims she was ovulating (tmi my apologies). So every call has been about him and her possible pregnancy with her claiming she has all of these symptoms that usually don’t happen until later on. It’s hard for me to tell her how I feel and that I wish she would talk less about it but she always gets mean and defensive. I feel like it’s hopeless at this point.

She rarely ever checks in on how I’m doing, whenever I try and tell her something about my day or week, she immediately changes the subject to something about her and her relationship. I had an attempt a couple weeks ago and she called ONCE to see how I was doing and then after that, nothing. I don’t want to cut her off because of my niece and nephew but I also can’t sit there and hear everything about herself because it’s all the time. Am I an asshole for wanting to be selfish for once? I think I am but I don’t know… I just need boundaries and they are so hard to set up for her because she always tears them down. I’m just really struggling here.