Taking everything you say at face value, the options for Ukraine are:

1. Take a deal that maybe you can't trust, but it at least gives you time to breathe.
2. Keep fighting, and with the war going how it is eventually lose more than what you've already lost.
3. Attempt to draw other states into the conflict so that you have a shot at what might be considered a victory, likely years more down the road under the best of circumstances.

There is no justification for 2, and 3 is highly unlikely -- if other states haven't entered the war already, they're not going to do so now.