Feeling neglected and insecure

My husband and I have been together for 13 years, and our baby is 3 and a half. We’ve talked off and on about polyamory, as we are high school sweethearts and each others firsts, so to us it makes sense to still be curious about other people since neither of us have experience outside our relationship. Over the years my husband’s health has declined and he has multiple chronic conditions that make it physically painful and often impossible for him to help out around the house. I’ve done my best to step up and now manage everything: all the chores, cleaning, cooking, childcare, and caring for him as well as my self and my full time job. I spend every moment I am awake doing some form of chore or childcare or task, and over time I’ve gained a lot of weight and don’t feel very attractive anymore. I’m the top in our relationship too, which is fine and all because my husband isn’t interested in switching roles or showing much of an interest in my body. I am willing to do all of this because I love him and our family and he means the world to me… But within the last week, he’s told me very honestly that he’s developed a crush on a friend he’s known for about 6 months, and that he feels he’s fallen hard for this person and wants to meet up with them and explore the waters of having this person as another partner. On one hand I’m not particularly jealous because in our past discussions, he’s also totally okay with me having another partner for myself, but on the other hand I’m extremely jealous because he’s already talking about flying across the country over Valentine’s Day weekend to go on dates with his new beau, calling him on the phone for hours each night, and playing video games together. I’ve also got this sinking feeling that he’s been flirting with this new person more because I’ve become less available due to the amount of work and effort I’ve put into maintaining our family in addition to my own career, that I’ve been so exhausted and depressed that I haven’t had energy or motivation for much else. We don’t have any family or close friends in the area to help with child care either, and no funds for dates or babysitters or anything enjoyable. I’m feeling abandoned and neglected and unappreciated, and very alone because I haven’t told anyone I know personally about this because I’m afraid they won’t understand or they’d be judgmental and have cruel things to say about the love of my life. I want to support him and I think it’s so wonderful that he has such a large and loving heart… but I just don’t know how I feel or what I want to do about this. I want help around the house and I want to be flirted with and taken care of, but I feel like it’s unfair for either of us to ask that of the other. I just wanted to vent, thanks for reading this long post if you did, gonna go have myself a little cry while I lay the baby down, again.