my dream is dead and I just need to complain

For my entire life, since I was literally around 5 years old, I have wanted to be a pro barrel racer. For those who don't know, its a horseback riding sport, a rodeo event, where the fastest time wins. I have my own horse and we have done a few competitions but nothing big or exciting, just fun shows. I am 18 as of right now, and I know I seem young probably to a lot of people but in order to get into and be good at equestrian sports you have to grow up in it and start competing when you're like 10. I didn't get that luxury, and while I am INCREDIBLY grateful for my horse, I love him dearly, he's 20 now and has arthritis, so we can't compete anymore. I would MUCH rather him be healthy than me be selfish and compete anyways. Barrel racing was the most fun I have ever had in my entire life, and each competition we did was so so so much fun. I haven't done a competition in around a year or so now, and I didn't go to college for rodeo because I didn't grow up in it and wouldn't have made the team regardless, I ended up staying home for community college. I love community college honestly and again I'm so grateful for my horse. But my dream is crushed. I can't help feeling hopeless. It's too late for me, I can't go pro, I can't BE anything in that field anymore. I have 3 younger siblings and we don't have a trailer so I can't do more competitions even if my horse was able. I have no goals, I don't even want to ride anymore. I haven't wanted to do much of anything physical in so long because of this and I'm gaining weight and I just really feel like what's the point? My point was barrel racing, and that's not going to happen. What do I do without an ultimate goal? What is the meaning of life now? I spiral about this shit almost daily and I'm crying as I write this. I'm medicated, used to go to therapy, I have an amazing boyfriend and a career idea, but nothing will ever replace the passion I had before and I really just don't even know what to do with myself anymore. Why? Just why are we here if we can't live out what we feel we were born to do?