On a long-term impulse/hope that having a pet again would make me feel better, I adopted a cat. I was unable to care for him properly so he was rehomed last week, only a month or so after adoption. I feel tremendous guilt and shame for putting the cat through this; I was absolutely sure about the adoption at the time, but as soon as we got home and he started paying attention to other family members I lost my interest and started avoiding him.

It's been two weeks and the thought of a pet being helpful to my situation has come up again. This time I thought of smaller animals: rats. My roommate said I will need to convince him, so I prepared a presentation for him that included all pros and cons of having a pet rat.
At the end of it he said: "well what do you expect me to say to this?" First trigger.
He finished with: "I will in no way be responsible for them." Final hit.
 I feel rejected and ashamed. I think I might be splitting? I feel... inferior and humiliated, even though I know he absolutely had the right to say he doesn't want to do anything with them.
I'm less sure of everything now. I don't think I can be a responsible pet owner. I think I'll harm them, I don't trust myself, especially now that I don't really have his support. I'm spiralling.