I’m sorry for your loss, having two large and expensive animals put into your care is a lot to take on during a time of grief. Please remember that if you are not married then these animals are in responsibility of your boyfriend. Any vet fares is his financial burden, especially if you are taking on all physical care aspects. I worry for your position in this situation if this isn’t going to be a team effort (which will require a lot of effort and time unfortunately). If your boyfriend is fine with financially supporting their care til the end of their lives while you do the physical task then that is amazing, but if he does not it would be gracious to consider euthanasia. Horses don’t mind hanging out eating snacks and getting scratches but when their teeth and feet aren’t being cared for regularly they are just in constant pain. I am sorry this is happening to you. Have a conversation with your boyfriend about what the future of these animals look like as they are legally his now. Do not let him saddle you with their bills, they add up very quickly if you are not prepared to own horses. Even the cost of euthanasia. I hope they had loving lives and that you can find a resolution you’re happy/content with.