Clearly being unhappy in an abusive relationship isn't better than anything; not better than being single, not better than being in a good relationship. But I think the comparisons can be skewed, in that you're not comparing like with like. My relationship with exH wasn't abusive all the time; at the start, and for nearly 20 years, it was fantastic, he was my complete soulmate, funny and caring and supporting and sexy and I thought we'd love each other forever. But then he changed; a combination of PTSD which he refused to address, and alcoholism to try to cope with the PTSD (which helped a lot, not).
I've been single now, on and off, for about five years. I don't want another relationship, I like my independence too much, and I'm not lonely. But sometimes, and it's only sometimes, I miss him. I miss the smell of his skin, and the way we would finish each other's sentences. I miss the times when he'd hoist the DC up onto his shoulders and we'd walk by the sea hand in hand. Then I give my head a bit of a wobble, because I'm not missing the person I left, I'm missing the boy I fell in love with at school, and the man I married and who I was going to grow old with. I'm not missing the scary one, the one hollowed out by the drink until there was nothing left but a bitter, angry shell, the one who bullied the children and hit me. I'm missing the life I would have had if everything had turned out right, not the life I really had.
Yes, it's lovely being in a good relationship, and yes, it's sometimes tough being single, but being single and lonely is massively, massively better for me than being in a relationship that - truth to tell - wasn't even abusive all the time. So very much better than constantly worrying about whether tonight was the night he'd turn round and yell at the DCs, or wave a knife at me, or even just pass out drunk. Only you can decide, OP, whether it's better for you to stay or to leave, but the overwhelming impression I get from those who've made the choice to leave, is that it's been the best thing for them.