Fren, your question hits home for me - my wife lost her brother to suicide. Here is what I can tell you:
Salvation is possible for someone who takes their own life. In fact, God says, "Greater love hath no man than this, that he lay down his life for his friend." A soldier who willfully falls on top of a grenade, knowing that it will kill him, to save others has committed the greatest act of love known to humanity - not sinned.
Who can know what was in your son's mind when this occurred? Only God. And only God can answer you, "Yes," or "No." My suggestion is to ask the Lord that question, and ask Him to answer you by giving you peace in your soul that your son is with Him in heaven. God has a way of answering such questions - He answered it for my wife.
Her brother took his own life out of great grief and depression over a very difficult thing that occurred in his life with his family; I won't go into details but it was savage enough to destroy his will and mind. Your son sounds like he had a similarly hard road. If their fight led them to an early death by their own hand, even if only to stop the misery of oppression by the demons of this world, there is a good chance that the will of their hearts and minds (being mentally afflicted with such difficulties is something I am morally convinced makes every difference to the Lord), then chances are very good that he is in the presence of the Almighty today, rejoicing and waiting your reunion.
God bless, fren.