Not really sure how to feel about this

Hello, I’m 24 years old. With two kids, 14 month old and a 3 1/2 month old. Yea I know... crazy. But that’s the thing, I feel like I’m going crazy. I’m a SAM my husband works 8am-7pm. Long hours. We live 3 hours away from our family. I take my daughter at night so he get a full nights rest for work. His work requires a lot of thinking. But my energy is getting low. Very low. Some days I feel like “yea i got this mom thing” and others.. well other days I want to fill up my bath tub and just stick my head in it and just drown myself, but then I feel guilty for thinking that because my kids need me. My husband feels like i have bipolar disorder, I just feel like I’m going out of my mind. On rough days i think about suicide. Nobody knows I feel this way. I feel like it’s getting worse..