Malai is either used as an object ( Mumyle malai pitnu bhayo-My mom beat me.) or when expressing feelings (Timlai dekhera malai ekdamai khusi lagyo-I am happy to meet you/Nice to meet you.)
Ma is used as I in english.(Ma student ho- I am a student) Ma is also used as me. But only when you want to say "Hey, it's me." - Oie ma ho. Me is not used as an object. Malai is the word to use.
Maile is equivalent to I in english. Yes, ma is also I but "maile" is only used when you are doing an action (well MOST of the times). To be sure, use "maile" with things in past tense.
Maile phone gare- I called. NEVER say Ma phone gare.
Maile phone gardai thiye.- I was calling. You CAN say Ma phone gardai thiye.
Maile phone gareko thiye- I had called. NO ma here either.
Ma phone garchu/Maile phone garchu. (I call)
Ma phone gardai chu. Maile phone gardaichu. ( I am calling)
Maile phone gareko chu. (I have called) NEVER Ma phone gareko chu.
Ma/Maile phone garnechu. ( I will call)
Ma/Maile phone gariraheko hunechu. (I will be calling)
Ma/Maile phone gareko hunechu. (I will have called) EIther one is fine.
Hope this didn't confuse you more.
Good luck with your Nepali!!
Eg.