No longer want to be with him.

I'm a current SAHM with a special needs little boy. I'm 18w2d pregnant and I'm just not in love with my SO anymore. But I literally have no one else and no current income of my own due to my son being severely autistic so I stay home with him. I know if I stay with my SO, I'm going to be miserable but I feel stuck. We don't really get along and lately he just irritates me really bad.

Any advice? Especially if you ever had to start over as a single mom. I'm at a loss.