If I don't talk to somebody about this I won't be able to solve this problem by myself.
If I don't talk to somebody about this I won't be able to solve this problem by myself. For me, it's a big deal.
ご質問ありがとうございます。
「誰かに相談しないと私一人では解決出来ない」は英語で「If I don't talk to somebody about this I won't be able to solve this problem by myself.」と言います。
また、「それほど私にとっては大きな問題なんです」と追加したいなら、「For me, it's a big deal.」と言えます。
最終的に「If I don't talk to somebody about this I won't be able to solve this problem by myself. For me, it's a big deal.」という風に言えます。
ご参考になれば幸いです。