おもいきって、主語（subject）を「僕（boku)」に変えてみました。どうかな？

私が悲しい！T_T

僕は悲しい！T_T

は＆が：if it is "ga",　the thing which is focused wouldn't be the fact you're sad but who is sad.Try to read my correction below remembering this. :-)

私ただ「とらドア」を見るよ！「とらドラ」はすごい、でもエンヂングは悲しいよ！私はなきますよ！アアアアアアア、とらドラ！！！T_T
I just watched "Toradora"! "Toradora" is amazing, but the ending is sad! I'm crying! AAAAAAH, TORADORA!!! T_T

僕はちょうど今「とらドア」を見たところです。とらドアはすごいけど、エンディングが悲しすぎる！大泣き中です。あーーーーーーとらドラーーーーーー！！！T_T

ちょうど今＋Vたform＋ところ: just did something

けど、: means "but" just like でも、しかし、だけど. Hoewever, it can be placed after adjective and verbs like that, while others can't.

いadj い + すぎる: means "too"+ adjective. its a common expression especially among the young recently. It is originally used as a negative way but its changing and is used as a positive way as well. ex)kawaisugiru / utukushisugiru + noun. Ever heard?

大泣き中です。:I changed just because it sounds more natural. it simply means, I'm crying out now.

－－－－： Its actually the both is correct. In just case you don't know that we use this symbol(?) a lot.

どのアニメは私を見ているか？私を悲しいアニメひつよういません。私ひつようハッピーのアニメ。さ、みんなさん、どのアニメ私を見られるか？
Which anime should I watch? I don't want a sad anime. I want a happy anime. So, guys, which anime should I watch?
僕はどのアニメを見るべき？悲しいアニメは要りません（いりません）。たのしいアニメがいいです。さあ、みなさん、僕はどのアニメを見るべき？

Sth + を ＋ transitive verb: Do Sth like watch anime.. other example) ピアノを弾きます（play the piano)、ごはんを食べます（eat meal)

Vじしょform+べき：shuld do something

要りません（いりません）: I changed just because it sound more natural in this text. it simply means "don't need". 必,kanji, means something like abosolute/definate. If you want to use 必要, 必要ありません is correct.

いadj + noun : 美しい馬（うつくしいうま beautiful horse),おもしろい人(funny guy)

ハッピーな is actually not Japanese( because happy is not japanese) but its なadj these days.

なadj + noun : so you are right. ハッピーなアニメ is correct.

What do you thinkg using "boku"? Watashi is a kind of all-powerful thing though.

Okay, this were written in an outburst of extreme sadness, since I just finished a really good anime. So I probably made some really brutal mistakes up there. So, please, could you correct me? And also tell me which anime should I watch now? Thanks! またね～