Not being able to get it up with my baby mom

Me and my baby mom have been broken up for 4 years. We stopped having sex for about a year. but now when we do I get nervous and I have a hard time getting and keeping an erection. I only really have this problem with her. Before I use to be Rock hard just from the thought of her. I don’t really know what’s going on. I’m still super attracted to her. Anyone else go through something similar?