You say that all your dreams'd be crushed if she had the foal: that's a huge statement! It's hard for me to evaluate the situation when I don't know what your dreams are, if they're truly life-long goals, if in fact there's a way to have the foal & fulfil the dreams as well (that you haven't thought of), etc.. You also say that having the foal could be good for you--? I'd list the pros & cons, since there seem to be both, & choose the weightier side. You also need to be apprised of pregnancy/delivery risks to the mare, & figure that in, as well as whether it's good for her emotional health to go through with a pregnancy at this time. Why would this have to be her last foal? Then, too, would you regret it if you had the foal aborted? Would an abortion put the mare into emotional/chemical trauma?