Nothing in tonights episode made any sense

I'll be talking about the Speed Force Time Travel Energy in this (which is a lot more powerful than regular Dimensional Barrier Breaking Energy) so be forewarned it will be technical. When a speedster needs to travel in time the speedster needs to build up enough Speed Force Energy to break through the Dimensional barriers of the multiverse and past/future. Reaching certain speeds can cause different uses of the Speed Force Energy and the outcome caused by that energy. As seen in the latest episode, to which we are talking about in this thread Barry calculates how fast he needs to be traveling to use the Speed Force Time Travel Energy.

The episode 1x15 where the Flash runs and sees himself running, he continues with his day until the hurricane incident. While running at that top speed making a wall to hold back the hurricane he accidentally tapped into the Speed Force Time Travel Energy briefly. When he used this speed and traveled back a day he made a causality loop timeline. When he traveled back, that timeline fizzled into non-existence the moment he goes back and the new one took over from that point thanks to the speed force time travel energy (this event by the way keeps happening). Much like how Eobard Thawne is still alive even though Eddie died, the timeline Eobard comes from is still intact up until the moment he gets trapped in the past and has to live as Harrison Wells.

When Barry goes back to talk to Eobard-Wells about being faster to beat Zoom once again he had to do the calculations for speed force time travel energy being used so he just goes back as an observer as to not disrupt the timeline as much as possible. He does this anyway and when he goes back to the future, his original timeline no longer exists, and so he becomes a remnant from another timeline...

Now when Barry goes back and saves his mom he created a paradox "Flashpoint" which started catching up with him. Previous timelines we had already encountered were erased because he changed a fixed point in time which was suppose to happen and had always happened. It affected everyone majorly. A timeline where Barry never became the Flash, so if he never became the Flash, he wouldn't exist in the future to return to save his mom and he wouldn't need to return to save his mom because Reverse Flash wouldn't exist to go back in time and kill her. Barry however retains Flash powers during Flashpoint (only temporarily) because that timeline hadn't set yet, but was starting to (his memories changing). Had he stayed in that timeline he would of forgotten his past memories and lost his powers. Due to Eobard Thawne still being in his aberration timeline he'd still exist up until the point the Speed Force catches up with him and removes him from existence (as seen in DC's Legends of Tomorrow).

That was my long answer.

The short answer to all the time travel questioning also could just be the writers using the "Speed Force" to explain it. The Speed Force is beyond time, space and matter. It has it's own rules and can manipulate all around it.

Sorry if this doesn't clarify any more. This has been my attempt at explaining what the writers are trying to show the audience. Or well what the audience is suppose to deduce.