I would suggest that you get prepared to lose a chunk of your fleet, as here is what you could attempt to do (may not work, but i have done this before, and it helped me a lot):
Get the planets that is connected to that choke point 2 star bases each, and get all the star-bases weapons, life, and self-destruct ability to their max. Then launch a full scale attack on the choke point (with your ally as well) and try to focus all your attacks on the enemies capital ships and titans (be aware of the titans location at all times). If you are winning, then you should be able to take a few capital ships down and a good portion of the fleet (leave when their titan shows up, if it's there at all times, then you have to jump in,attack, and leave before it gets to you). However, if you lose this attack, and your fleet is crippled beyond belief, then you return to your closest planet, and you wait for the enemy to come (this is why you have your star bases):
Position your fleet so the enemy must go near the star bases, get ready to trigger the self-destruct ability on them (try to get the capital ships in the explosion, and the titan if it comes, but your goal is to get the titan alone, or make it so it runs). As soon as you feel the enemy will take the most damage, self-destruct a star base. Then wait again, then when ready, trigger the second star base. If the enemy focuses the star base. then let the base take the damage a bit, and attack the enemy fleet. (remember, you have the Ankylon's hull/shields, and it's ultimate ability (use it to slow your enemies rate of fire)).
If all goes well, you should be able to push their fleet back, but if not, go back to another planet and detonate the star bases.